THE LANAI EARTHQUAKE OF FEBRUARY 18'11. Doak C. Cox. Environmental Center University of Hawaii. January 1985

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1 THE LANAI EARTHQUAKE OF FEBRUARY 18'11 By Doak C. Cox Environmental Center University of Hawaii January 1985

2 ABSTRACT From an extensive compilation of the reported effects of the large H&waiian earthquake of February 1871, it is concluded that the earthquake occurred at 22:11 on 19 February Honolulu local time (08:42.5 on 20 February Gr'benwich time); that its epicenter was probably south of Lanai within 60 km of N, W; and that it had a Richter magnitude of Considering its probable epicentral location, it seems appropriately referred to as the Lanai earthquake. Probable average intensities of the earthquake on the Modified Mercalli scale are estimated at IX on Lanai, VII to IX on East Molokai, XI to VIII on Maul; IV to VI on Hawaii; VI to VII on Oahu; V on Kauai; and IV on Niihau.

3 CONTENTS INTRODUCTION REPORTED NATURE AND EFFECTS In Honolulu Elsewhere on Oahu. On Molokai On Lanai. On Maui On Hawaii On Kauai On Niihau. At sea Aftershocks TsWlami concerns ANALYSIS OF REPORTS Date and time of occurrence Duration and character of motion Estimation of intensities and previous estimates Intensi ty Scale Previous estimates Comments on intensity estimation. Revised estimates of intensities in various areas In Honolulu. Elsewhere on Oahu On MolQkai. On Lanai. On Maui On Hawaii On Kauai On Niihau Summary Intensity distribution and source Previous source estimates.. Methodology of estimation of intensity distribution and source Preliminary source estimation Allowance for effects of site conditions, source rupture length, and focal depth. Final estimation of intensity distribution and source. Discrepancies between calculated and estimated intensities, and uncertainties in source estimation

4 Number and intensities of aftershocks SUpposed tsunami CONCLUSIONS ACKNOWLEDGEMENTS. REFERENCES.,. Page APPENDIX: Modified Mercalli Intensity Seale of

5 TABLES Reported times of occurrence and durations and directions of motion of the 1871 earthquake Previous estimates of Modified Mercalli intensities of the 1871 earthquake. Comparison of previous and revised estimates of the Modified Mercalli intensities of the 1871 earthquake Shallow subsurface materials prevalent at places of reported effects of the 1871 earthquake... Estimated Modified Mercalli intensities of aftershocks of the 1871 earthquake A-I. Modified Mercalli Intensity Scale of 1931 A-2. Modified Mercalli Scale of 1931, abridged version A-3. Modified Mercalli Scale of 1931, 1956 abridged version FIGURES Location map, places on Oahu... Location maps, places on Molokai and Lanai. Location map, places on Maui Location map, places on Hawaii Location map, places on Kauai. Intensity distribution of the 1871 earthquake as estimated by Cox and Morgan (1977). Reestimated intensity distribution of the 1871 earthquake assuming a point source... Intensities of the 1871 earthquake in relation to epicentral distance

6 1 INTRODUCTION The earthquake that had the highest intensities on Oahu In historic times was one that occurred on 19 February This earthquake 'was one of three in Hawaiian history whose Richter magnitudes, as instrumentally determined or estimated, were 7 or greater. the other two, occurring in April 1868 and November 1975, were centered on the southeast coast of Hawaii and therefore had considerably lower intensities on Oahu than that of The effects of the 1871 earthquake were most severe on the islands of Lanai and Molokai and on the western coast of Maul, and its center has, therefore, been considered to have been in the vicinity of those islands. This report on the 1871 earthquake has been prepared for use by a 'Fask Force established by the Natural Hazard Group of the University of Hawaii to investigate the issue of the seismic risk zone to which Oahu should appropriately be assigned in the building code of the City and County of Honolulu. The Oahu intensities of the 1871 earthquake are of particular Interest in this investigation because seismic risk zone assignments in building codes are based on expectable earthquake intensities and the expectation of intensities is influenced particularly by the highest intensities of record. A general review of the historic earthquakes that have been significant on Oahu will be presented in Cox et al., (in prep.). The issue of the Oahu seismic zone designation will be dealt with in Berg et al., Un prep.). The character and effects of the earthquake on all of the Hawaiian Islands from Niihau to Hawaii except Kahoolawe were described in contemporary Honolulu newspapers; and a reliable account of the earthquake and its effects, written soon after its occurrence by W. D. Alexander, was published in the American Journal of Science (Alexander 1871). The earthquake has been included in most lists of important Hawaiian earthquakes (eg. Eppley, 1965; Furumoto et al., 1973; Coffman et al., 1982); and analyses of the reported effects of the earthquake in terms of its intensities at various places and their implications with respect to its magnitude and epicentral location have been published by Furumoto et ala (1973), Cox and Morgan (1977), Furumoto et ala (1980) and Furumoto (1983). The-importance of the earthquake, particularly in relation to earthquake expectancy on Oahu, is so great, however, as to warrant still another analysis of its intensities and, incidentally, its magnitude and epicentrallocation, using all available contemporaneous descriptions of its effects. It is not easy to obtain access to original issues of the newspapers, although they are on file in a few libraries and archives. Microfilms are more readily available, but are difficult to read. Hence it seemed desirable to make the pertinent contemporary information on the earthquake available more conveniently in the form of absracts and quotations in this report. The contemporary accounts quoted or cited in this report are, in addition to Alexander's, those in the two English-language newspapers that were being published at the time in Hawaii: the Pacific Commercial Advertiser ( predecessor to the present Honolulu Advertiser), and the Hawaiian Gazette ( ); and also those in two Hawaiian-Iangc'?ge newspapers: Ke Au Okoa and Ka Nupepa Kuokoa. All of these newspapers were weeklies published in Honolulu. English translations of the Hawaiian-language articles on the earthquake, prepared originally by Esther T. Mookini for Augustine S. Furumoto of the Hawaii Institute of Geophysics, were made available by Furumoto for the restudy of the earthquake; and the quotations attributed in this report to the Ke Au Okoa and Ka Nupepa Kuokua are actually taken from Ms. Mookini's translations with a few alterations made recently by her to provide requested clarification. The locations of the places mentioned in the various accounts are shown in Figures 1 through 5.

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8 3 REPORTED NATURE AND EFFECTS In Honolulu (Figure 1) The first published account of the earthquake was probably that in the Gazette issue of 22 February. The following description of the earthquake at Honolulu is quoted from that issue: Our citizens were not a little startled on Sunday evening last, at seven minutes past ten o'clock by the most severe shock of earthquake which as been felt on this island within the memory of anyone!lving. The shock was preceded by a rumbling sound... The motion of the earth seemed at first to be perpendicular, but gradually changed to horizontal. The duration of the earthquake wave is difficult to determine--opinions vary. GenUemen, whose first thought, after the intimation of an earthquake actually occurring would be to observe its direction and other peculiarities, differ in opinion in this respect. It seems to be settled that the direction was from the eastward, but whether from the north or south of east, is a question which no one can decide, except for themselves. The peculiarity of this earthquake, was the duration of the vibrations and the gradual increase of violence from the first vibration to the point of culmination. It was not, as is generally the case, a sudden and violent vibration of the earth, lasting for a few seconds only, but lasted with visible force fully fifty-five seconds. Up to at least the forty-fifth second of the vibration, the violence of the shock increased, and those who had before experienced similar convolutions of nature, began to enquire of themselves when it was going to end and what rapidity of motion mother earth would attain before she stopped No great damage was done by the earthquake, although several buudings showed signs on Monday morning of a severe trial. Among the most severely "shocked" buldings were those at Punahou, all of which were more or less damaged. The walls were severely cracked and the chimneys thrown down.' It will probably be necessary to repair and strengthen the walls to make the buildings safe for occupation. In town, the Court House walls were somewhat injured. The walls of the Queen's Hospital were somewhat injured, besides several other buildings, among which was the store of T.C. Houck, the wall on the south end of which was seriously damaged. The building on Maunakea Street known as Liberty Hall, was much injured. The walls of several other buildings were slightly cracked, but none seriously. None of the larger buildings in the city show any signs of damage. Very little loss was sustained by falling crockery and glassware, although we hear of several instances where crockery and statuary were thrown down and broken. It is somewhat singular that nearly all of the losses suffered, of this nature, were on or in the vicinity of Kukui Street. The Au Okoa of 23 February, which reported the time of occurrence of the earthquake as "between seven and eight minutes after the hour of 10", stated that "The very old people who are living today could not recall an earthquake equal to this one." Its statements as to the duration and change in character of the earthquake vibrations were so similar to those in the Gazette that they may be assumed to have come from the Gazette or the same informant as that consulted by the Gazette. However, the Au Okoa stated that initially there was a "rustling movement from northeast to southwest", after which "the house tren:bled as if all the sides were cracked indeed as if a basalt rock fell from the Pali for that was how the rustling and thumping felt. On solid earth strong bodies were tossed about as if in a pond overlaid by waves.1t The Au Okoa agreed that:

9 4 In the earthquake of last Sunday night the city did not suffer much serious damage, however on Monday morning some houses showed open cracks. Among the buildings badly shaken were Punahou's school buildings. There were fractures in the walls and chimneys collapsed. In the city there were no major damages. The walls of a house had a fracture, the hotel at Lepakaholo was damaged as well as the court house. In some houses below Kaopuaua, window panes and stone figures collapsed and were totally destroyed, being torn apart and smashed to bits. According to the 25 February issue of the Advertiser, "The latter half of Sunday had been cold and blustering, the wind blowing in gusts from the northeast"; the earthquake had occurred during a lull in the wind, and ttthe premonitory rumbling noise" was thought by many to be Itt he roar of the wind through the treees". Others, however, "wondered at the circumstance of drays rushing down street at that hour on Sunday night." The Advertiser agreed with the Gazette that the initial motion was "an up and down movement, short and quick. To this succeeded a series of horizontal jerks, sufficiently powerful to cause a perfectly sober person to stagger in attempting locomotion." According to the Advertiser, the violent motion continued only 30 seconds but was followed by quite perceptible oscillations lasting for several minutes, and the vibrations were oriented "from south of east to north of west." The vibrations continued so long as to make the strongest minded people apprehensive, to frighten these naturally nervous and timid, to cause some to faint or go into hysterics, and to cause some to fall on their knees and pray. The "swinging motion" that succeeded the rattling of windows and doors produced nausea in many and vomiting by a few. Like the Gazette and Au Okoa, the Advertiser considered the damage to buildings remarkably slight. In addition to the damages to buildings reported earlier, the Advertiser reported cracking of the walls of Kawaiahao Church and the International Hotel, a stone building. The Advertiser also reported that considerable crockery and glassware was thrown down and broken in private residences; that "only a few clocks whose pendulums swung east-west were not stopped"; that "The proprietor of a hennery at Kalihi reported that all of his fowls were shaken off their roosts"; and that "Capt. McGregor, who keeps the light on the reef, received the impression that a vessel had run foul of the tower. tt Other than the premonitory rumble, the only precursor of the earthquake noted by the Advertiser was a lightening of the sky "just before the shock was felt", nas if the moon was about rising", seen by several observers who were out of doors at the time. No one seems to have noticed any unusual animal behavior before the earthquake, and "While the motion of the earth subsided, the thousands of dogs... were silent as the grave, but when it was over, they set up a clamor.1t Followers of a Hawaiian prophet, Kaona, "of whom there are quite a number living in an about the city, came to the conclusion that the predictions of their prophet were about to be fulfilled, and that the end of the world was right at hand. So in order to let the angels know that they were on hand and waiting, the commenced tooting horns, which they kept up during the night at intervals." According to the Kuokoa (25 February): Seven minutes past 10 this past Sunday night houses rattled, the earth rumbled, and in no time, the earth was shaken. We believed this earthquake on Oahu was a significant thing since it's strength was evidenced in the trembling. We heard some skeptics quickly awoke from sleep, turned to the walls to pray and repent. Some others ran swiftly outside, without any clothes and just sat down. Still others called out the very last words of a repenting man, "Oh my God, come". There were a lot of good insignificant things we heard of but suffice it to say here that you will have your fill. Some people believed the earthquake moved in the way our islands were laid out, trembling from the southeast to the northwest. Who is to verify this.

10 5 In Honolulu the places damaged because they were caught by surprise were as follows: the front of the doctor's house at Hopemana cracked open; the plaster on the gable in back of the court house fell down; the house of Lepekaholo split open; Punahou also was damaged; and the plaster in Kawaiahao's Sunday School fell down. The bending and swaying of the earth took a long time; the ones with stop watches argued long. Some people said it lasted twenty seconds or more, others said fifty seconds more or less. The side of Queen's Hospital and T.C. Houck's store were also damaged. Several windows at Mokimana's store were broken as well as other damages. Concerning the nature and effects of the earthquake in Honolulu, Alexander (1871) wrote: In regard to the direction of the shock, the motion was chieny vertical with a rocking movement northeast and southwest. It was compared by some to the sensation of riding a "bucking mustang" or driving a cart over a rough corduroy road. Many stone and adobie buildings were badly cracked, particularly our school house, the large stone church, the Queen's hospital, and the court house, and the northeast and southwest walls were generally most shaken. Stone fences running northwest and southeast were thrown down, while those at right angles to this direction were not injured. Doors facing southwest were swung open, and hanging lamps were left swinging for ten or fifteen minutes in almost every instance in the same direction, viz. from northeast to southwest. Considerable crockery was broken, and heavy articles of furniture displaced. The usual roaring sound preceded this earthquake. Persons who were on board ships in the harbor report that they heard this terrible roaring sound far out at sea, and then the ships that lay farthest out were first struck and afterward those that lay at the wharves. They agree that the vessels were first drawn violently out to sea and then in the opposite direction. Several persons of undoubted veracity insist that they saw a nash of light on Punchbowl hill the moment before the earthquake commenced. H1sewhere on Oahu (Figure 1) The Hawaiian Gazette on 1 March noted that, although the severity and duration of the earthquake were unprecedented everywhere on Oahu, its intensity seemed to vary from place to place. The effects reported at vari<..as places included: At Nuuanu Pali: a rockfall obstructing the Pali road (Gazette, 22 February; Au Okoa, 23 February; Kuokoa, 25 February); At Kaneohe: The collapse of the eastern wall of the Protestant church (Gazette, 22 February; Au Okoa 23 February; Advertiser, 25 February; Kuokoa, 25 February), causing a hole about 20 feet wide; fall of plaster in Rev. B.W. Parker's house (Kuokoa, 23 February); east-west slopping of milk from pans (Alexander, 1891); At Waimanalo: A rock fall from the Pali, causing no damage to houses (Kuokoa, 25 February); At Hwa, breakage of cast iron pillars supporting the belfry of the Catholic Church and collapse of the belfry (Gazette, 1 March); At Waianae: A fissure (Au Okoa, 23 February); severe intensity and landslip carrying a house several rods (Alexander, 1871i. At Waialua, comparatively slight intensity (Alexander, 1891).

11 6 On Molokai (Figure 2) The most detailed account of the earthquake on Molokai available is that in the following letter published in the Advertiser on 4 March: Pukoo, Molokai, February 21, 1871 P.C. Advertiser-A very severe earthquake occurred at this place on the 19th inst. The shock commenced at 5 minutes to 10 P.M., and lasted about 60 seconds. It commenced with a dull roaring noise, accompanied by a violent rocking of the earth, increasing to a louder roar and a lively rattle of things generally, and finally subsided with a low rumbling sound. During the shock, my house was fearfully shaken. The vibrations were from south to north. Crockery could not have been insured at less than 100 percent premium. At Kupeke, a half mile above here, the earth cracked open for a distance of several rods, and the stone houses in the vicinity are cracked in every direction. In many cases, lamps were overturned, shelves cleared of the contents, and pickles and pie fruits lay around loose in charming confusion. At Kaluaaha, a small addition on the northwest corner of the old Mission house, (stone) was thrown down, and a portion of the east gable end came down, crushing through the verandah roof below. Near there, a portion of the north wall of a stone house, the property I believe of the Catholic Church fell, and on the east side, the wall bulges out even with the eaves. The parsonage suffered more or less in the falling plastering, as did every house in this vicinity, where plastering is used. The large stone church at Kaluaaha, in common with all stone buildings in this region has suffered more or less in cracked wall and damaged plastering. Stone walls are down in every direction. In one place on the shore, a hole about two feet in diameter by eighteen feet deep, was formed by the earth sinking. The oldest inhabitant has been duly interviewed, and solemnly declares this to be the first time that mother earth has ever conducted herself in this fashion on Molokai, within his recollection. T.E. Cook The Gazette (22 February) had earlier provided some of the information provided in the above account; the Au Okoa (23 February, 2 March), and Kuokoa (25 February) had reported that the walls of the stone church at Kaluaaha were not merely racked but had fallen; and the Au Okoa had reported also the fall of the walls "of the stone house of Awailua on the bank of the pond at Kupeke." Abel, a Pukoo correspondent to the Kuokoa (4 March), described a hole opened there as 5 feet deep and 3 feet in circumference (?) at the top but 9 feet in diameter below. He also described what may have been the "hole" on the shore mentioned by the Advertiser, stating that this extended "one chain and five links" (about 70 feet). According to Abel, an "old stone house of Mr. Hitchcock which our police chief was living in was broken into pieces." Kamana Nuakea, the proprietress of a store at Kupeke reported (Kuokoa, March 4) that: "Glasses, plates, and bowls in my store were destroyed, falling all over my store. Stone houses were split; stone fences were strewn in destruction as if broke by man. The government road that runs close to my place split. Its length was perhaps 2 chains long" (about 130 feet). Other effects reported on Molokai were: a) the destruction of the t1"ail that led to Kalaupapa from the top of the Pali on the north coast (Gazette, 1 March; Au Okoa, 2 March; Alexander, 1891); b) the breaking down of parts of the massive stone wall of the Kalamaula paddock, four feet wide and five feet high (Gazette, 1 March); and c) the occurence of a "thumping, rocking, tilting motion at Kalae" that threatened to overturn the house of the Gazette's (1 March) informant. Alexander (1871) considered that the earthquake was most severe at the west end of the island.

12 7 On Lanai (Figure 2) The most extensive account of the earthquake on Lanai is that in the following letter published in the Gazette (1 March): Palawai Valley, Lanai, Feb 21, 1871 Mr. Editor: We felt a shock of earthquake on this Island on the night of Sunday, the 19th inst., so violent that J doubt not it must be owing to some extraordinary outbreak on Hawaii, and J hasten to send to you, for general information, some particulars of the phenomenon, as observed at this point. I was roused out of sound sleep by the first shock, and immediately observed the time to be 10:16 P.M. I found it difficult to keep my feet, and felt a motion and heard a roar and rattle, as though I was in a railway train rushing onward with great speed. My family were reminded of precisely the same sensation. It lasted about 40 seconds, and created in that short time a lively alarm and excitement. Natives rushed out of their huts, calling to one another throughout the valley. Animals as well as people were greatly excited, frightened sheep ran down the hill with a great outcry, and the howl of the dogs added to the din and terror of the night. This first great shock was succeeded by several milder tremblings of the earth, and by reports or detonations in the direction of Hawaii, and at the same time bright glares of light were observed in the eastern sky, like displays of electric, or other luminous gaseous phenomenoa, in the direction of the great mountains. This earthquake is declared by the oldest natives of the Island to be by far the most violent and forceful ever felt by them on Lanai. The shock of April, 1868, was very light here, and scarcely noticed by a few, but this one roused up every soul on the island, shook it from vale to peak, and racked and rent its bold, rock ribbed coast. A great portion of the well known bluff, Pali Kaholo, has fallen into the sea, enormous fragments have broken from those towering ocean walls between Manele Bay and Kamaiki Point; masses of the red basalt have been torn from the beetling turrets of Puupehe, the lone sea tower near the southeastern end of the Island; huge boulders have been hurled from the mountain sides, and the ravines are filled with debris of rocks and trees and slides of earth; several great clefts have been opened in different parts of the Island; and it has been shaken and broken as though the mighty elements of the earthquake were surging and upheaving at its very foundations and ready to burst forth with volcanic fury, and convert its lovely valleys once more into flaming, sulfurous crater. W.M.G. On Maui (Figure 3) Several letters providing detailed accounts of the earthquake at and near Lahaina were published in the newspapers. That from an unnamed correspondent quoted below was published in the Advertiser on 25 February:

13 8 Lahaina, Feb. 22, 1871 MR. EDITOR.-The 4th day of February 1871, and the 19th day of February 1871, are days ever to be remembered in Lahaina. The first was the occasion of a free fight, before mentioned, and the other the great earthquake, at 10 o'clock 15 minutes P M on Sunday. It came as near from the S.E. as you could have made it. We heard the noise like distant thunder, long before we received the shock, and when it came, it came good. There is not an adobe or adobe and stone, or a stone house but what is cracked, and some so shattered so bad that it is dangerous to live in them. The old mission church is damaged, the walls are all cracked. Also the fine stone building of Col. Spalding is damaged. Then as you come along the main road, that is cracked open for many feet. Then along the Court House, which is damaged, and will need repairing. So you may go the whole length of Lahaina, and see the effects, until you get to the end, where the road and other places are all cracked open. We must have fire near us somewhere, or why should the ground be cracked, unless it was to let the gases out. Both sugar mills in Lahaina have iron chimneys and are well braced, so that there was no damage done in that direction. Since Monday night, we have had repeated shocks, but light. I cannot find out by anyone that the sea was affected, everyone was too much frightened to take any notice. In most of the stores, you would see that the goods principally on the south side were thrown off, but those that were on the north side were thrown against the wall. When the shock came, it was with a sudden jerk, then trembling, and ending with rolling as if you were on board of a vessel. Our "Moral Town" has had such a shaking, that no one remembers the like before. But all is quiet in the front. We have had cloudy weather since Sunday, but as yet no rain. The mills are hard at work and turning out plenty of sugar as well as a beautiful quality. Respectfully yours, &: c. Much of the information in the above letter is corroborated by two other letters or excerpts from letters published in the Gazette of 1 March without the names of the correspondents or dates. The first was: On Sunday evening, while making a call in company with Governor Dominis upon Mr. Dickerson and family, just as we were about to make our adieus, the house began to tremble a little, increasing in force until the earth rocked to and fro like a tub in a pond, the shock lasting more than a minute, I should think. During the worst of it, Mrs. Dickenson seized the lamps and extinguished them, to prevent fire. I got out of the house, and some others did the same. When the shock was over, we got a light, and ascertained the time to be 10 o'clock 15 minutes, exact, by Lahaina time, corrected only the day previous. I believe everyone was affected as by sea sickness. I was, certainly. I was unable to tell from which way the shock came; Mrs. Dickenson said from the south; Mrs. Dominis said the same; many said north; and few from the sea, while others said from the mountain. The motion must have been most severe from north to south, for bottles and glasses were tumbled all over from shelves ranging east and west, while those ranging north and south showed very little breakage. The ground opened up in one place, showing a mark in the morning. The Court house walls are opened, and much of the plastering is down; some adobe houses are pretty much demolished, and hardly any stone houses have escaped damage. I have not heard of anyone being hurt, up to 4 o'clock P.M. Monday. Almost everybody owns up to a bad scare, with two or three exceptions of very brave men,-and these appear to have rushed about in a rather unaccountable manner, unless it might be they were hunting for a place to stand to maintain a proper balance of the globe. I hope I may never experience another shake like it. The sea did not appear to be affected by the shock.

14 9 The second was: I have been in this country thirty-five years, five of them on Hawaii, and never have I experienced a shock so severe as this last has been. On Sunday night, at 5 minutes past 10, I was awoke by the shock. The house was rocking to and fro so violently that I could not get out of bed, and continued for over 1 i minutes, though some say 2 minutes. The vibrations appeared to proceed from north-east to south-west. There were successive shocks; one slight one at 20 minutes to 1, and one at 36 minutes to 12. As far as I know, there is not a single stone or adobe house in Lahaina that has not been injured. Our Court house is cracked in several places, and many of the adobe houses are in ruins. Some people say that shock was felt on Monday night: I did not feel it, but I decidedly felt one on Tuesday night at 12 o'clock. J.W. Kuhelemai of Lahaina, in a communication dated 2 February published in the Au Okoa (2 March), reported: - Two more letters from Lahaina were published in the Au Okoa (2 March). According to the first, from an unnamed correspondent but dated 22 February: There were earthquakes in other places but this was the first time an earthquake was experienced here.. the old ones said that they have never known such a strong earthquake as this one as also is my knowledge. The earthquake rumbled, grumbled, and cracked like thunder and violent winds. Some houses were flattened, some places on the road were cracked open. The walls of the government house cracked open and pebbles and plaster fell all over as well as inside the room When the earthqauke passed, people assembled to pray to God due to the strangeness of God's actions and His great generosity for not breaking open the earth to swallow them. According to the second letter, whose date is obliterated in the microfilm of the newspaper but whose writer was identified as J.W. Kuhelemal: This town was shaken by the earthquake for over a minute. Damages were to eight stone houses that I saw which broke and collapsed. There could have been more A section of earth split open. The length from end to end of the place that was cracked open measured 48 feet. This place that was cracked open is close to the pier between the street that rises to the new fort and the street that goes down and emerges at the government house beach. There was a house that was cracked open on its southeastern side as well as at its northwestern corner. In addition to the first of the letters from Lahaina, the Advertiser (25 February) published the following from nearby: Lahainaluna, Feb. 22, 1871 EDITOR ADVERTISER-The earthquake of Sunday evening was severe at this place. My house is shaken literally to pieces, although the pieces have not all come down. The end walls are started clear, and part of the north wall has fallen, also the whole south wall of the kitchen. To jump out of bed with your house thrashing itself to pieces, thoroughly dispels all one's past calm serenity in earthquakes.

15 10 The direction of the wave was evidently from south to north, or perhaps northeast. Fence walls au fell north. Crockery and medicines on shelves lying north and south were undisturbed. The contents of shelves lying east and west were thrown out. Clocks stopped at a quarter past ten. Mr. Andrew's house has had the northwest corner opened out. I leave Lahaina people to report for themselves. They look as if they had been through a bombardment. H.E. BISHOP (The first initial of the correspondent's name was probably misprinted. He was probably Sereno E. Bishop the superintendant of Lahainaluna Seminary.) Another letter from Lahaina, published in the Gazette (1 March) without the name of the correspondent or date, but so similar to the last that it was probably from Bishop, noted that It a wardrobe, standing east and west, flung out its contents and packages of stationery were thrown from shelves adjacent to the medicines, but standing east and west. An east and west wall of 60 rods is down in twenty places, the stones all falling north." T.H. Malihinihele, in a communication published in the Kuokoa (25 February) reported that stone walls at Olowalu, undisturbed by the earthquake of April 2 (1868), were tumbled by the 1871 earthquake. Z. Kaupalolo reported from Waikapu (Kuokoa, 25 February) that this!twas the first time a strong earthquake was known here according to a sixty-year old man. D.K. reported from Walluku (Kuokoa, 25 February): we, inside our houses, were frightened at the swaying of an earthquake. It was like four trembles at the time. If the time of the quake was a bit longer then several houses in Wailuku would have fallen down which was the strength of the thing that struck. The rumbling was like the sound of a gun. We have never known an earthquake before with such strength, this was the first time. This was the latest from Wailuku in the shelter of the valley. Concerning the earthquake elsewhere on Maui, the Gazette (1 March) reported: From Makawao, East Maui, one correspondent says that the shock of the 19th was the severest that he has felt during a residence of forty three years on this group. No special injury seems to have been sustained at Makawao. At Ulupalakua, south side of East Maui, the character of the shock would seem to have been nearly similar in strength and duration to that experienced at Makawao and Wailuku. A little more information on the earthquake on at Wailuku and in the western slope of Haleakala was added by Alexander (1871): At Wailuku, on the east side of West Maui, the earthquake was much less severe, stone walls being thrown down in some places but no serious damag~ done. The time by my father's cl3rk, which is set by the sun, was m P.M., equivalent to about m Honolulu mean time. At Makawao on East Maui the shock was slight. At Capt. Makee's, on the S.W. side of Haleakala, it was much less severe than at Lahaina. A train of molasses kettles was displaced, which was about the only damage done.

16 11 Although the intensity of the earthquake on the east slope of west Maui and west slope of Haleakala seems to have been smaller than that in the Lahaina vicinity on the west slope of west Maui, the intensity seems to have been high on the east slope of Haleakala. L. K. Kamakea, in a communication not published until 1 April (Kuokoa) reported the following effects in the Hana area and to the west: At Kaeleku: Collapse of stone walls including that around the school house, which was undamaged; At Wananalua: Ringing of the bell of the Protestant Church; At Kapueokahi, collapse of a stone wall; At Pukuila, collapse of a sea cliff, damming a spring; At Muole and Koali, collapse of "the sea cliff at Kanakiu and a cave called Halekumulani used to store canves, crushing 3 canoes, and threatening the lives of P. Momoa and his chiefess Mrs. L. Opunui who were pulled out of the rubble on the 20th; At Wailua: Collapse of the cliffs at Paihi and Honolewa, blockage of the government road, and injury to three cows and a horse; At Keanae, collapse of the cliff at Waiaolohe and blockage of the stream at Kawaikau. On Hawaii (Figure 4) The greatest detail on the character and effects of the earthquake on Hawaii is that in the following letter from an unnamed correspondent published in the Gazette (March 1): KAWAIHAE, February 21, 1871 On Sunday evening last, at about eight minutes past ten, we were terribly alarmed by a shock of earthquake, which appeared to me to be fully as severe as the shock at the time of the Kau outbreak. This shock lasted about 2! minutes, and was most peculiar in character. It commenced in the usual way, with a rumbling noise, reached its greatest intensity, and decreasing in strength until almost its termination, when it gave a most violent shake and suddenly ceased, seeming to be as if two earthquakes had merged in one. It has thrown down nearly all the stone walls in the district. Marshal Parke (who arrived here last night from Kona,) reports that the earthquake was very severely felt in Kailua,-in fact drove him out of the Governese? house, he fearing that it was about to fall. He also reports shocks of earthquake at 7 o'clock 11 minutes on Friday evening, 17th inst., and on Saturday morning at 5 o'clock. Neither of these shocks were perceptible here. We anxiously await news of our Hilo friends. At Waimea, inland from Kawaihae, the shock would seem to have been some degrees less severe than on the sea-board; and crossing the Island to Hilo, we learn from that town that the shock, though passably strong, was not of a character to create any special alarm. Essentially the same information concerning the effects at Kailua, probably from the same source, was published in the Au Okoa (2 March), which identified the house occupied by Parke as that of the chiefess Kiaaina. Alexander (1871) reported: "From Kohala I learn that the shock seemed to come from the reef, that some stone walls were shaken down, but the stone church and plantation chimney remained uninjured."

17 12 On Kauai (Figure 5) Very little information concerning the earthquake on Kauai was published in the newspapers. According to the Gazette (1 March), which did not identify the place affected: Its motion was of a complex character, thumping and vibrating, as if the houses were tilted from side to side. No serious damage, however to either buildings or inclosures was done, so far as we have heard. The duration of the shock is thought to have been from 30 to 40 seconds. The Au Okoa (2 March) reported that the earthquake was strong at Koloa and Wahiawa and elsewhere, but that houses and walls were not greatly damaged. It quoted a letter from Waimea that described graphically the shaking and sounds, and the widespread public concern, and stated that: "Some people have said they saw coconut trees flying from places they were planted." There were reports from two correspondents to the Kuokoa (4 March), one from J. P. Nuikino who reported that rocks tumbled down from the cliffs inland of Mana, and one from J. T. Lono who reported, inconsistently, that at Anahola: "The houses were overturned, however, there were no damages. Alexander (1871) reported: "From Kauai I hear that it was severe at Koloa on the south side of the island, but less severe and light on the north side at Hanalei." On Niihau The only known report of the earthquake on Niihau is that of a correspondent, M. W. Keale, to the Au Okoa (16 March): On February 19 at 10 minutes before 10 O'clock an earthquake shock the island of Niihau two times. The first quake was very strong and the second even stronger shaking all stationary things. It lasted a minute. At sea The earthquake was not felt only on land. According to the Gazette (22 February): The schooner Annie experienced the shock in the channel between Kahoolawe and Lanai. The vessel was wrenched and shaken in a most unaccountable manner. Those on board at one time supposed that it was "all over" with the vessel and with them. After the shock was over, and the vessel gilding [sic] along smoothly, search was made for any damage which might have been sustained. It was found that the rail amidship on the starboard side, had been split in a most unaccountable manner. Essentially the same accounts were published in Au Okoa (23 Feburary), the Advertiser (25 February), the Kuokoa (25 February), and by Alexander (871). The Advertiser indicated that the "Annie" was on her way from Kona to Honolulu and at least 12 miles offshore between Kahoolawe and Lanai. Alexander described the "Annie" as "in the channel south Of Lanai," and the Au Okoa, put her "just off the pali of Kaholo" on the southwest coast of Lanai. Seaquake effects were also felt by vessels in Honolulu Harbor. Advertiser (15 February): According to the Apprehensions were expressed that there would follow a tidal wave from the ocean, and some rushed down to the wharves, but learned nothing unusual, beyond the fact that the crews on board the shipping had experienced a sensation as though the vessels had suddenly grounded on the reef.

18 13 Aftershocks The only earthquakes mentioned as occuring before the large one of 19 February were one in Kau, Hawaii on the night of 15 February (Kuokoa, 11 March) and the two that Marshal Parke reported at Kailua-Kona on Hawaii: at 19:11 on 17 February and at 05:00 on 18 February. These places on Hawaii are so remote from the area most affected by the large earthquake that the earlier earthquakes probably cannot be considered foreshocks of the large one. There were, however, many reported aftershocks: 1) The "several minor tremblings of the earth" felt on Lanai that were reported by W.M.G. in her letter of 21 February (Gazette, 1 March) as following the large earthquake, probably during the night of the 19th to 20th; 2) "Two or three distinct, though very slight shocks" that were felt in Honolulu at about 21:00 on 20 February (Gazette, 22 February), that may have been included among the shocks reported in 3) and 4) below; 3) "Several slight shocks lt felt in Honolulu on 21 and 24 February (Alexander, 1871); 4) Frequent slight shocks feit on Molokai between 19 February and 3 March {Advertiser, 4 March}; 5) An earthquake reported in Honolulu at 23:45 on 3 March (Advertiser, 4 March); what the Advertiser (11 March) considered the same earthquake, felt more severely on Molokai, although reported as occurring there at midnight; and an earthquake reported felt on Maui and Hawaii at midnight (Au Okoa, 9 March), probably the same as that felt on Molokai; 6) Several earthquakes felt in Kau, Hawaii referred to in the Kuokoa of 18 March and the Au Okoa of 23 March. At Honolulu, according to the Advertiser: Tsunami concerns Apprehensions were expressed that there would follow a tidal wave from the ocean, and some rushed down to the wharves, but learned, nothing unusual, beyond the fact that the crews on board the shipping had experienced a commotion as though the vessels had suddenly grounded on the reef. At Lahaina, according to one of the correspondents to the Advertiser (25 February): "everyone was too much frightened to take any notice whether the sea was affected"; but according to another: "the sea did not appear to be affected by the shock." Alexander (1871) stated that: "No earthquake wave of any consequence is reported from any quarter."

19 14

20 15 ANALYSIS OF REPORTS Date and time of occurrence Although dated 18 February in the title to Alexander's (1871) letter that was supplied by the American Journal of Science and in a table in Furumoto et al. (1973), the 1871 earthquake clearly occurred on 19 February (Eppley, 1965); Furumoto et al. 1973, text; Cox and Morgan, 1971; Furumoto et al., 1980; and Furumoto, 1983). The reported times of occurrence of the earthquake (Table 1A) ranged from 9:55 to 10:16 p.m. There was no standard time system in Hence it must be assumed that these times were local times. Differences among the local times at the various places from which the reports emanated undoubtedly account for some of the differences among the reported times of occurrence. More important probably were lapses between the line of the beginning of the earthquake and the times when people checked their watches and clocks, and watch and clock errors. The most reliable time is suggested by Alexander's (1871) report that, at Honolulu, "In regard to the time, Flitner's astronomical clock stopped at 10h 11 m 17 s P.M." Considering that the clock might have been stopped by the Rayleigh waves of the earthquake, the first motion may have been at about 22:11 Honolulu local time, equivalent to about 08:42.5 on 20 February Greenwich time. Duration and character of motion The reported durations of observed motion of the earthquake (Table 1B) indicate principally the unreliability of estimates of periods of time. Again the most reliable statement is probably that of Alexander (1871) pertaining to Honolulu: "In regard to the duration of the shock, Rev. G. Williamson, Dr. J. Hutchinson, Judge Hartwell and one or two others who timed it carefully, agree within a few seconds of making it 55 seconds." The changing character of the motion with time described in a few of the reports suggests recognition of the successive arrivals of the various phases of the earthquake. However, the only report implying quantitatively an arrival-time difference is that of the earthquake at Honolulu in the Gazette of 22 February. If reliance could be put on that difference, 45 seconds, and if it were interpreted as the difference between the arrivals of the P and R phases of the earthquake, it would indicate that the epicenter was somewhat less than 150 km from Honolulu. As will be shown, possible epicentral locations estimated by other means are about 110 to 120 km from Honolulu. That the difference was that between the arrivals of the P and S phases, which would suggest an epicentral distance of about 450 km, is much less probable. The direction in which the front of the earthquake moved could not have observed, and statements such as that in the Gazette (22 February) concerning the direction at Honolulu presumably relate to the predominant direction of motion of the principal vibrations, perhaps those of the Raleigh waves. As expectable, there were considerable differences of opinion as to the direction even at a single place (Table lc). Estimation of intensities and previous estimates Intensity Scale As appraised in the contemporary newspapers and by Alexander (1871), the 1871 earthquake was strongest on Lanai, Molokai, and West Maui; less strong on Oahu, East Maui, and the western and northern parts of Hawaii; and weakest on Kauai and the eastern part of Hawaii. On the basis of the effects of the earthquake at various places, semi-quantitative estimates of its intensities at those places may be made by reference to the Modified Mercalli (MM) intensity scale of 1931 (Wood and Neumann, 1931), a scale in which, conventionally, the intensity is expressed in 12 discrete steps indicated by the roman numerals from I to XII in order of increasing intensity. Complete description of the effects symptomatic of the 12 steps

21 16 Table 1. Reported times of occurrence and durations and directions of motion of the 1871 earthquake. A. Times of occurrence Place Honolulu, Oahu Pukoo, Molokai Palawai Valley, Lanai Lahaina, Maui Lahainaluna, Maui Waikapu, Maui Wailuku, Maui Hana, Maul Kawaihae, Hawaii (Kailua?) Kona, Hawaii Hilo,Hawaii Kauai Niihau Time, p.m. 10:07 10:07-10:08 10:06-10:08 10:11 9:55 10:00 10:16 10:05 10:08 10:15 11:00 10:15 10:20 10:20 10:30 10:08 10:05 10:15 9:30 9:50 Reference Gazette, 22 February Au Okoa, 23 February; Kuokoa, 25 February Advertiser, 25 February Alexander, 1871 Cook in Advertiser, 4 March Abel and Nuakea in Kuokoa, 4 March W.M.G. in Gazette, 1 March (1 in) Gazette, 1 March Au Okoa, 2 March (? in) Gazette, 1 March Kuhelemai in Au Okoa, 2 March Bishop in Alexander, 1871 Kaupalolo in Kuokoa, 25 February W.P. Alexander in Alexander, 1871 Kamakea in Kuokoa, 1 April Gazette, 1 March Au Okoa, 2 March Parke in Alexander, 1871 Hitchcock in Alexander, 1871 Lono in Kuokoa, 18 March Keale in Au Okoa, 16 March

22 17 Place Honolulu, Oahu?, Molokai Pukoo, Molokai Palawai Valley, Lanai Lahaina, Maui Kawaihae, Hawaii Hilo, Hawaii B. Durations of motion Duration 55 sec. 30 sec. severe + several min. 55 sec. 45 sec. 60 sec. 40 sec. 1t (or 2) about 1 min. 21- min. about 1 min. Reference Gazette, 22 February Au Okoa, 23 February Advertiser, 25 February Alexander, 1871 Gazette, 1 March Cook in Advertiser, 4 March W.M.G. in Gazette, 1 March? Gazette, 1 March Au Okoa, 2 March Alexander, 1871 (? in) Gazette, 1 March Alexander, 1891 C. Predominant directions of motion Place Honolulu, Oahu Kalamaula Paddock, Molokai Pukoo, Molokai Lahaina, Maui Lahainaluana, Maui Wailuku, Maui Kawaihae, Hawaii Direction From eastward From northeast to southwest From south of east to north of west From northeast and southwest West by north South to north From south, from north, from sea, or from mountain From south to north or perhaps northeast From north to north or SE tonw From northeast or sea From reef Reference Gazette, 22 February Au Okoa, 23 February Advertiser, 25 February Alexander, 1871 (? in) Gazette, 1 March Cook in Advertiser, 4 March (? in) Gazette, 1 March Bishop in Advertiser, 25 February Alexander, 1871 (? in) Gazette, 1 March Alexander, 1871

23 18 in the original version of the MM scale are shown in Table A-I. The descriptions in an abridged version of the scale published with the complete version are shown in Table A-2; and those in a 1956 abridged version developed by Richter (1958) in Table A-3. Where distinction Is necessary, intensities implied by the original complete version will be identified in what follows as MM 31 and those implied by the 1956 version as MM 56. Continuous-valued variants of the MM scale have been used as well as the discretevalued original M:vI scale. In what follows, arabic numerals will be employed to indicate intensities in the scale used in this way. Although usage has varied (see Cox, 1964) intensities characterized by a particular roman numeral are treated in this report as represented by the intensities between a half-unit smaller and a half-unit larger than the corresponding arabic integer (eg. intensity VII represents the range from 6.5 to 7.5). Previous estimates Previous estimates of the MM intensities of the 1871 earthquake at various places are compiled in Table 2, and a map showing the intensity distribution estimated by Cox and Morgan (1977) is shown in Figure 6. All of the estimates shown in the table are based on the descriptions of effects compiled by Furumoto et al (1973). The intensities suggested by Macdonald (1973) are drawn from an unpublished critique of the report by Furumoto et al. (1973), a critique of which Cox and Morgan (1977) were unaware. - - Table 2. Previous estimates of Modified Merealli intensities of the 1871 earthquake. Place Furumoto et al Macdonald 1973 Cox and Morgan 1977 Furumoto et al Furumoto 1983 Kauai IV IV V Oahu Western part Eastern part Molokai Lanai Maui vn vn* vm vm vm VI VI vn vn VI vn vm vm vm vn* vn-ix vm vn vn Hawaii Kohala Kawaihae Hilo IV vn VI-vn V vn-vm IV In Furumoto et ala (1973) and in Furumoto et al. (1980), specifically at Honolulu.

24 19 Comments on intensity estimation Macdonald (1973) commented on the uncertainty of assigning MM intensities "on the basis of descriptions in a century-old newspaper", noted the tendency of the users to exaggerate the effects of unusual events, and questioned "the possibility of assigning an accurate intensity of at all" to the 1871 earthquake. The assignment of MM intensities is somewhat subjective even in the case of a presentday earthquake for which responses have been obtained to questionnaires systematically distributed in the area where it was felt. High accuracy is impossible to obtain. However: a) Estimates of long-term earthquake risk cannot safely be based on the records of the short-term during which the results of modern seismological investigations are available; b) The MM intensity scale was designed so as to make it useful in estimating intensities from the kinds of earthquake effects commonly noted; and c) The information available on the effects of the 1871 earthquake in many areas is quite comparable with that available for many other pre-1900 earthquakes in other parts of the world for which estimates of intensity on the MM and similar scales have been made and used in earthquake-risk assessment by competent seismologists and earthquake engineers. As will be seen, the differences between the intensities estimated by Furumoto et al. (l973) and those estimated by Macdonald (1973) represent, in many cases, differences Tn interpreting the implications of reported damages to masonry buildings and stone field walls. Both Furumoto et al. and Macdonal.d presumably related these damages to descriptions in the abridged 1931 version of the MM scale, a further abbreviated version of which was included in the Furumoto et al. report. Better descrimination between the intensities implied by such effects is possibleby reference to the types of masonry distinguished in the 1956 version of the scale. Revised estimates of intensities in various areas The intensities of the earthquake place to place have been reestimated in this study from the more complete descriptions of the effects compiled in this report. There is comparatively little evidence of exaggeration of the effects of the earthquakes in most of the reports, but to avoid overestimates of the intensity by acceptance of an exaggerated accounts from an area, description of effects as described in apparently independent reports from the same area were compared in so far as possible. With reference to the masonry types distinguished in the definitions of intensities in the 1956 version of the MM scale, it has been considered that none of the stone buildings existing in Hawaii in 1871 represented construction of Type B, that many of them represented Type C, and that some of them as well as the adobe buildings represented Type D. The stone walls of the time in the fields were not bonded by mortar, and although many of them were well constructed otherwise, few if any of them had stones laid in such a way as to tie the entire thickness of the walls together. The stone walls have, therefore, been considered to represent either Type C or Type D masonry. In Honolulu There seems little question that everyone in Honolulu felt the earthquake and that most if not all were frightened, and hence that its intensity was at least MM VI. Not all ran outdoors, but some of those that did were so alarmed that they ran out "without any clothes", and some who did not "turned to the walls to pray and repent" (Kuokoa, 25 February), reactions that would suggest a possible intensity of MM31 vn. The reactions seem, indeed, to represent an approach to panic that is symptomatic of intensity MM31 VII. However, it must be recognized that the reactions were probably more extreme than those that would have been

25 IV o 10 miles Nuuanu Pa 11 tla 1 rrana 1 0 Figure 1. Location map, places on Oahu.

26 21 displayed under similar circumstances at a place where large earthquakes were more frequent. The difficulty people had in walking (Advertiser, 25 February) also suggests an intensity of at least VTI, and possibly VII (MM31), although there were no reports of persons experiencing the difficulty in standing that is characteristic of intensity MM 56 VII. Some experience with nausea is symptomatic of an MM31 intensity of only II. However, the extent of nausea, leading to actual vomiting by a few {Advertiser, 25 February indicates surely a much higher intensity. The swinging of hanging lamps and the stopping of clocks might be accounted for by intensities of only IV and V, respectively. The destruction of crockery, might be accounted for by an intensity of only V or VI. The comment in the Gazette (22 February) that in Honolulu no great damage was done by the earthquake, and one in the Advertiser (25 February) that: "The damage to buildings was, contrary to expectation, quite small," seem clearly to reflect a contrast between what people expected considering the felt intensity of the earthquake and what actually resulted, rather than an opinion that the damage was inconsequential. Of greater importance in intensity estimation are the specific damages to masonry buildings. The buildings in downtown Honolulu that were reported damaged include at least eight that were definitely of masonry construction or may be assumed so from the nature of the damage: Courthouse: walls somewhat injured (Gazette, 22 February; Au Okoa, 23 February; Kuohoa, 25 February; Alexander, 1971). Queens Hospital: walls somewhat injured (Gazette, 22 February; Kuokoa, 25 February); badly cracked (Alexander, 1871). T.C. Houck's store: south wall seriously damaged (Gazette, 22 February, Kuokoa, 25 February). Liberty Hall (Maunakea Street): much injured (Gazette, 22 February). International Hotel: walls cracked (Advertiser, 25 February). Kawaiahao Church: Walls cracked (Advertiser, 25 February) (probably same as) "the large stone church lt : badly cracked (Alexander, 1871). Kawaiahao Sunday Sehool: plaster fell (Kuokoa, 25 February); badly cracked (Alexander, 1871).. Doctor's house at Hopemana: front cracked open (Kuokoa, 25 February). Esther Mookini, the translator of the articles in the Au Okoa and Kuokoa, considers that the ITLepakaholo hotel" (Ilka hotele rna Lepakaholo" originally translated lthotel at Lepakaholo") that was damaged (Au Okoa, 23 February) and the "Lepekaholo house" Esther Mookini, the translator of the articles in the Au Okoa and Kuokoa, considers that the ITLepakaholo Hotel" ("ka hotele rna Lepakaholo", originally translated "hotel at Lepakaholo, that was damaged (Au Okoa, 23 February) and the "Lepekaholo house" (Ilka hale Lepekaholo," originally translated "Lepekaholo's house") which was "split open" (Kuokoa, 21 February) were the same, that spellings of the name of the structure represented transliterations of "Liberty", and hence that the damages referred to in both newspapers were to the Liberty Hall (see above), a saloon and rooming house. Damages to downtown buildings whose construction is unknown include the breaking of windows and other damage to Mokimana's store (Kuokoa, 25 February) and the smashing of windows and stone figures at ITsome houses below Kaopuana" (Au Okoa, 23 February).

27 22 According to Spencer Leinweber and Glenn Martin, architects who have special interests In historic Honolulu buildings, quarried coral blocks had been used in the construction of many ot the buildings in existence in Other masonry types used were field rock, brick, and adobe. Quarried lava did not come into use until about Still standing, among the masonry buildings damaged by the earthquake are Kawaiahao Church, which was constructed of coral blocks, and the Kawaiahao Sunday School which, if it was what is now known as the Kawaiahao Schoolhouse, was constructed of adobe. Although the total number of masonry buildings in downtown Honolulu at this time is unknown, it appears that the majority were either undamaged or suffered damages so slight as to be not worth reporting. Among those still standing, but not reported damaged, although built before 1871, are the Chamberlain House and the Print Shop of the Congregational Mission and the Melcher Block at Bethel and Merchant streets. There is partial confirmation ot the reports that all of the building at Punahou School were more or less damaged, their walls being "severely cracked and the chimneys thrown down" the damage being considered probably sufficient to make it necessary to repair and strengthen the walls (Gazette, 22 February, Au Okoa, 23 February). According to a history of the school during its first century (Alexander and Dodge, 1941): "A severe earthquake shock which sent the pupils running out of doors, Imuch wrecked' the Punahou buildings in February The trustees had first considered the advisability of insuring them in February, Now there was a proposition on foot to abandon some of them. There were at least two buildings or complexes of masonry construction in the Punahou campus in 1871: a) What was known from its plan as the "E building"; and b) what Alexander referred to as "our schoolhouse", a building still standing that is now known as 1I0Id School Hall". The lie-building", which had been constructed originally of adobe in 1843, had an adobe cookhouse connected opposite the center wing of the "Ell, but the corners of the IIEII had been replaced by Rice Hall and Dole Hall, constructed of coral in 1845 and 1848 respectively. The school house, Old School Hall, had been constructed in 1851 of volcanic spatter quarried on the campus, laid up with coral-lime mortar on coral foundation slabs. There was a chimney at the cook house, and there may have been one at a timber-construction residence, the Octagon. The adobe used in the Kawaiahao School House and in the E building at Punahou clearly constituted masonry of type D, and the masonry in several of the other buildings damaged was probably of this type also. 0 n the one hand, the cracking of masonry of type D would not necessarily signify an intensity greater then MM 56 VI. On the other hand, even allowing for some exaggeration in the reports, the "cracking open" of the wall of at least one house downtown and apparently two, the cracking of masonry so severely as to raise doubts as to the safety of buildings at Punahou, and the fact that some of the masonry cracked was probably of type C, would suggest an intensity of Vll. Recognizing that the majority of the masonry buildings in Honolulu were not significantly affected by the earthquake, the effects on buildings and the other reported effects, considered together, suggest an average Honolulu intensity approximately on the boundary between MM VI and MM Vll. Elsewhere on OahU The descriptions of effects elsewhere on Oahu are too meager to form the basis for good intensity estimates. The comparative lack of reports cannot in itself be considered evidence that the intensities were less than at Honolulu, because in the 1870's communications between Honolulu and the northeast, northwest, and southwest coasts of the island were as poor or poorer than those between Honolulu and the neighbor islands. Landslides may occur on the Nuuanu PaIi with heavy rainfall without earthquakes, and rock falls on the steep palls of Oahu do not need to be triggered by earthquakes. Hence the blockage of the Nuuanu Pall road and the rockfalls on the pah back of Waimanalo might individually, have resulted from an earthquake of considerably less than MM Vll. Together, however, they suggest intensity of MM VI on Vll.

28 23 As supposed by Macdonald (1973) the church at Kaneohe whose wall fell in was "one of the old mission churches, and the wall was of masonry, either bonded with mortar made of burnt coral limestone, or simply laid up without mortar and then plastered. These old church buildings are especially subject to extreme earthquake damage, as was shown in Kona in 195!. Extreme damage to them should not justify assignment of a high MM rating'. However, "Damage to masonry D, including cracksll is symptomatic of intensity MM 56 vn, and "fau of stucco and some masonry walls" is symptomatic of MM 56 VIII. If assignment of at least intensity vn to Kaneohe is not definitely indicated, it is only because, there probably being but one stone building in the area, the fall of the wall of that one cannot be regarded certainly as typical. The destruction of the belfry supported by cast-iron pillars at Ewa might possibly have required an intensity of IX. However, in the absence of specifications as to the pillars, it seems probable only that the intensity was at least VI there. Considering the instability of some of the soils in the Waianae district, the landslide at Waianae might be caused even by an intensity of less than vn. Although there is no supporting evidence, there is no reason to disbelieve Alexander'S statement that the intensity at Waialua was small. In summary, the reported effects of the earthquake in various places on Oahu suggest that its MM intensity over the eastern part of the island, including Waimanalo and Kaneohe, was about the same as that at Honolulu; that it was probably about VI at Ewa and Waianae; but that it may have been less than VI at Waialua. On Molokai The fall of crockery, overturn of lamps, etc. at Pukoo, at Kupeke nearby, and at Kaluaaha might have occurred with an intensity of MM VI. However, the extent of falling plaster suggests an intensity of vn, and the extent of damage to the walls of stone buildings suggests an intensity of at least MM VII and quite possibly MM VIn. Furumoto et ale (1973) referred to a "new fault about 2 chains long observed on the island of Molokai';:- The reference was undoubtedly to the "split" of this length on the government road at Kupeke, close. to Pukoo, reported by Nuakea (Kuokoa, 4 March). The "split", is probably more properly referred to as a fissure than a fault. The language used by Abel (Kuokoa, 4 March) in reporting on the "hole" at the shore at Kaluaaha is obscure. In the original translation it was described as "in the sea, one chain and five links dried..." suggesting the possibility that the earthquake was accompanied by shoreline emergence. However, reviewing the language to check on this possible interpretation, the translator~ Esther Mookini, indicated that it suggested instead, merely that the reported length was from dry land along a line approximately normal to the shore. Assuming that the width of the hob was much less than its length, this "hole" also might be referred to as a fissure. The fissuring at Kupeke and at Kaluaaha suggest strongly an intensity of at least MM 56 vm ("cracks in wet ground") and quite possibly MM 56 IX ("conspicuous cracks in ground). With respect to the damage to the stone wall of the Kalamaula paddock, Macdonald (1973) commented as follows: From my knowledge of similar paddocks, the wall was almost certainly constructed of loose field stone, and even though it was 4 feet thick stones probably had not been laid in such a way as to tie the entire thickness together. When walls are built in this way, with occae~onal stones running more or less through their entire thickness, they may be quite resistant to earthquake damage. Such is the case with the ancient walls at the City of Refuge in Kona. Such careful construction is rare in walls built during historic time in Hawaii; and these walls commonly show considerable amounts of raveling in earthquakes with local MM intensity much less than the 8 assigned the 1871 earthquake on Molokai by Furumoto et al.

29 N.j>. Kalae ~lolokai Kalamaula paddock (approximate) r 10 miles I Palawai settlement (approximate) Kaholo Point Figure 2. Location maps, places on Molokai and Lanai.

30 25 As Macdonald commented, " rock falls from cliffs and trail cuts are common in intensities at least as low as 5, and it would not take a large landslide or rockfall to destroy the trail down the pali to Kalaupapa or at least make it impassible." However, the effects on the trail do not prove that the intensity could not have been considerably greater. The racking of the house at Kalae, not far from the head of the trail (probably a frame house) suggests an intensity of at least VI and more likely vn or greater. In summary, it appears that the intensity of the earthquake was at least VIn and quite possibly IX in the general vicinity of Pukoo, and at least VI and more probably vn or vm in north-central Molokai. No accounts have been found providing evidence that "the shock was especially severe, especially at the west end" of Molokai as reported by Alexander (1871), and it seems possible that "west" was substituted erroneously for "east" either by Alexander or by the printer of his letter. On Lanai The difficulty W.M.G. (Gazette, 1 March) had at Palawai Valley in keeping his feet is symptomatic of intensity vn, as is the extent of alarm he reported. As Macdonald noted, a single rockfall such as he described on the sea cliffs and valley walls of Lanai would be of little significance. However, the fall of "a great portion of the well known bluff, Pali Kaholo" and the extent of the effects on Puu Pehe and the cliffs between Manele Bay and Kamanaiki, suggest an intensity of at least VIn, more probably IX, and quite possibly X, even if allowance is made for exaggeration in some of W. M. Go's descriptions of "ravines filled with debris of rocks and trees and slides of earth;" Itgreat clefts. opened up in different parts of the Island t, and other effects. On Maui The extent of alarm at Lahaina and the fall of medicines and other items from shelves at Lahainaluna would assure only that the intensity was at least VI of the earthquake at those places; and the destruction of adobe buildings at Lahaina and overturn of rock walls might possibly have resulted with an intensity of only Vll. However the extent of adobe-building destruction and the extent of damage to stone buildings at both Lahaina and Lahainaluna suggest an intensity of at least MM 56 VIn even if the masonry of the stone buildings was of type D. The fissuring of the ground in Lahaina suggests an intensity of at least VIII and quite possibly IX. However, the fact that the iron smokestacks of the sugar mills at Lahaina were undamaged, even recognizing that they were "well braced t suggests that the intensity was no more than VIII and possibly even less. The intensity of the April 1868 earthquake has been estimated as vn in the Olowalu and Waikapu vicinities by Furumoto et al. (1973), and as Viol' Vll in the Olowalu vicinity and Vll in the Waikapu Vicinity by Cox andmorgan (1977). Hence, the reports from Olowalu that the 1871 earthquake was stronger than that or 1868, and that from Waikapu that it was stronger than any within the memory of a 60-year old man, suggest that the later earthquake had an intensity of Vll or greater at those places. The intensity at Wailuku, Makawao and Ulupalakua seems clearly to have been less than that on the Lahaina area, but the damage to stone walls in fields at Wailuku suggests an intensity of at least VI and quite possibly Vll. The Wananalua church bell at Hana was probably a small one whose ringing might have resulted from an intensity no greater than VI; and a greater intensity would not be indicated by the collapse of a few stone walls in the fields or of a few sea cliffs. However, the extent of collapse of stone walls at Kapueokahi (apparently near Hana) suggest intensitil''3 of vn at those places. Rockfalls from the cliffs at Wailua and Keanae are frequent, and do not necessarily indicate high earthquake intensities. In summary, the effects reported on Maui suggest that the earthquake had an intensity of at least Vil, more probably VIn, and possibly even IX in the Lahaina area, but intensities of only about vn farther east on Maui.

31 N (j'\ Wailuku Waikapu Makawao MAUl Kaeleku _ 10 miles Ul upa 1 akua Figure 3. Location map, places on Maui.

32 27 On Hawaii The report that at Kawaihae the earthquake was "fully as severe as the shock at the time of the Kau outbreak" (Gazette 1 1 March) probably refers to the April 1868 earthquake whose intensity there has been estimated as VIII (Cox and Morgan ) or IX (Furumoto et ai., 1973), However, the stone walls in the vicinity could have been thrown down with an intensity no greater than VII and possibly even VI, and considering the lack of reports of damage there other than that to stone walls 1 it seems probably only about VII. The fact that stone walls at KohaIa were shaken down but the stone church and plantation chimney remained intact suggests that the intensity was no more than VII there also. The intensity at Kailua-Kona might perhaps have been as great, but an intensity of only VI could have led Marshal Parke and others to move outdoors. The intensities elsewhere cannot well be estimated from the reports, but that at Waimea seems to have been somewhat less than those at Kawaihae and KohaIa and that at Hilo considerably less, probably at IV and V. Figure 4. Location map, places on Hawaii.

33 28 On Kauai The!laying" of coconut trees "from places they were planted't that was reported from Waimea, Kauai, was surely grossly exaggerated. It would take no great earthquake intensity to tumble rocks from the cliffs inland of Mana. Although Alexander (1871) thought that the earthquake had been severe at Koloa, the Au Okoats reports suggest that although it was strong there and at Wahiawa, the damage it caused to houses and walls at those places was not significant. Probably the intensity of the earthquake on the south coast of Kauai was no more than MM V at the most. Neither Lonots internally inconsistent report from Anahola nor any other report provides a basis for either the rejection or support of Alexander's (1871) opinion that the intensity was smaller on the north coast than the south. 10 miles Figure 5. Location map, places on Kauai.

34 29 On Niihau The "shaking of all stationary things" described in the sole report from Niihau could be accounted for by an intensity no greater than IV. Summary The Modified Mercalli intensities of the earthquake from place to place, as estimated in the study, are compiled in Table 3. The values in roman numerals, identified as I in the table, are the integer values in the conventional discrete-step scale. The values in arabic numerals, identified as I' are values in the continuous-scale equivalent selected so that, at the outer boundary of a conventionally mapped isointensity alone, r = 1-0.5, and in general, l' = I = I' Associated with the average value of I' for each place or group of places is what is considered, the possible error in the estimate of the average, taking into account the number and consistency in intensity implications of the reports of effects at the place or group of places. It should be recognized that the actual intensity at a site underlain at shallow depth by particularly competent or incompetent material might differ from the average of sites at that place by more than the possible error. Intensity distribution and source Previous source estimates Purumotoet al. (1973) considered that the 1871 earthquake had a magnitude of about 7 and an epicenterllin the Molokai-Maui areaf!. Furumoto et al. (1980) considered that the magnitude was about 7.5 and that its epicenter was closer tomolokai than to Maui. Macdonald (1973) believed that the epicenters of both the 1871 earthquake and one in June 1948 were on the great submarine scarp northeast of Molokai and north of West Maul. Cox and Morgan (1977) accepted the magnitude estimates of Furumoto et al. (1973) and assumed that the epicenter was about midway between Maui, Molokai, andlanai (see Figure 6). None of these estimated magnitudes or epicentral locations have been considered definitive on the present study. IIIIIIIU '~ "1\,, fa:,'fl" ;r 50 I 150 In...,," lu"." '~Ull'Qto.t,I {lt7ll I Pigure 6. Intensity distribution of the 1871 earthquake as estimated by Cox and Morgan (1977).

35 30 Table 3. Comparison of previous and revised estimates of the Modified Mercalli intensities of the 1871 earthquake. Previous estimate Estimates from this stud! or range of Discrete estimates step Continuous scale (r) Place discrete step scale scale Probable Uncertainty (I) (I) average (+/-) Oahu Waialua, Waianae, and Ewa } VI-VII { VI Kaneohe to Waimanalo VI Honolulu and Punahou VII VI or VII Molokai Kalae vicinity } VII-IX { VII orvm Pukoo vicinity VII or IX Lanai Palawai vicinity to S coasts vm IX Maui Lahaina vicinity to Olowalu vm Waikapu to Wailuku VII-vm VII Makawao to Ulupalakua VI Hana vicinity VI or VII Hawaii } 1 Kohala VII VI Kawaihae VII-Vm VI Waimea VI Kailua VI Hilo IV-V IV or V Kauai South and east parts IV-V V Niihau Unidentified IV

36 31 Methodology of estimation of intensity distribution and source The results of a study by Howell and Schultz (1975) of the attenuation of the intensities of earthquakes with distance from their centers, permits use of the intensities estimated from the effects of the 1871 earthquake at various places in estimating the epicentrallocation, the magnitude, and a generalized distribution of the intensity of the earthquake. Howell and Schultz found that there were considerable differences among the characteristic rates of intensity attenuation of the quakes of three regions of the contiguous United States: a San Andreas province, a Cordilleran province, and an Eastern province. Furumoto et al. (1980) found the intensity distribution of the 1871 earthquake fit best by the intensity attenuation found by Howell and Schultz for the Cordilleran province. The Howell and Schultz relationships apply to the radii of the outer limits of conventionally mapped Modified Mercalli (MM) "isointensity" zones, the integer-valued intensities of those zones, and various functions of earthquake size. The relationship between intensity and the combination of hypocentral distance and magnitude used finally in this study was derived from three Howell and Schultz formulas, each of which allowed for the effects of both energy absorption and geometric spreading on intensity attenuation. The combination of the three formulas was modified to eliminate the limitation to the outer limits of conventionally mapped "isointensity" zones by use of the continuous equivalent of the MM scale, and recalibrated by fit to the intensities of some Hawaiian earthquakes with known magnitudes and hypocentral or epicentrallocations (Cox, 1984). The form ula used is: It = (M - 1) exp (a - b In r) where I' = MM intensity in the continuous scale, M = Richter magnitude, r = (x 2 + h2)i = distance from focal point, x = epicentral distance (more precisely the radius of a eir~le whose area is equal to that in which the intensity equals or exceeds I'), h = focal depth (assumed to be 14 km if not known) a = b = per In km c = per km Because both the epicenter and magnitude of the 1871 earthquake were uncertain, intensity distributions were calculated for various combinations of epicentral distance and magnitude, initially using relationships pertinent to the San Andreas and Eastern provinces as well as the Cordilleran province. Calculated isointensity lines for each combination were plotted on a transparency that could be layed over a map showing the estimated 1871 earthquake intensities for checking the fit between the calculated and initially estimated intensities. Preliminary source estimation It was obvious from the earliest trial fits that, as earlier estimated, the epicenter of the 1871 earthquake was in the general vicinity of the Maui group of islands, and that the attenuation of its intensity with distance was considerably less than that characteristic of San Andreas quakes and considerably greater than that characteristic of Eastern quakes.

37 32 Further trials confirmed the similarity between the intensity attenuation of the 1871 quake and that characteristic of Cordilleran quakes t and indicated that, with the exception of those at a few places, the estimated intensities corresponded reasonably well (closer than about one intensity unit) to those calculated if it were assumed that the quake epicenter were in the immediate vicinity or south of Lanai, and its magnitude were approximately 7. The exceptions were the intensity estimated for places on the Maul group of islands. With any assumed magnitude the discrepancies were greatest for assumed epicentrallocations north of Maui or Molokai or between those islands and Lanai and Kahoolawe, and least for assumed locations in the vicinity of Lanai or to the south or southwest of that island. Allowance for effects of site conditions, source rupture length, and focal depth To attempt to reduce the inconsistencies, three refinements of methodology were tried. First, recognizing that the intensity of the 1871 earthquake may have been significantly greater at sites underlain by poorly consolidated sediments than at sites underlain by bedrock, each place for which there was an intensity estimate was assigned to one of three classes on the basis of shallow subsurface materials prevalent in the vicinity as indicated in Table 4. Assuming that the intensities to which Howell and Schultz fit their intensity distributions included those at sites underlain by a wide variety of subsurface material, it was considered that an intensity calculated from one of the Howell and Schultz relationships would be that most likely to occur at a site underlain by moderately consolidated material, and that sites at the same epicentral distance but underlain by poorly consolidated material or by bedrock might be expected to have actual intensities a half-unit greater or less, respectively. Second, although the intensity distributions were initially calculated assuming the earthquake had a point source so that the isointensity lines were circles, it was recognized that an earthquake as large as that of 1871 probably resulted from a rupture along a fault of significant length. Analyses of the seismigraphic records of earthquakes of magnitudes as high as 7 or 7t often indicate ruptures on the order of 50 to 100 km even when there are no consistent surface evidences of the rupture. To investigate the effect of rupture length, a second set of transparencies was prepared with elliptical isointensity lines having foci separated by 75 km and having the same areas as the circles plotted on the first set of transparencies, and used in the sam~ way as the first set. Third, the effect of focal depth was investigated by the preparation and use of still a third set of transparencies with intensity distributions in whose calculation various focal depths were substituted for the common focal depth, h = 14 km, which had been assumed in the preparation of the first set because it had been found by Howell and Schultz to provide the best fit to the intensity distribution of Cordilleran earthquakes. No improvement in fit resulted from the attempt to allow for differences between the shallow subsurface conditions place to place. The fit to at least parts of the intensity distribution could be improved if the source were assumed an elongate rupture rather than a point or if the assumed focal depth were altered within the range 10 to 20 km. However, with any combination of assumptions there remained inconsistencies, particularly for places on Maui. For example, in no distribution fit to the estimated intensities elsewhere was there so great a difference in intensity as that between Lahaina and Wailuku. Final estimates of intensity distribution and source The intensity distribution considered best fitting the estimated intensities of the 1871 earthquake is shown in Figure 7. This distribution was based on the point-source assumption, an epicentral location at N, W, on the southwest coast of Lanai, a Richter magnitude of 7.0, and a focal depth of 15 km. The curve of calculated intensities, assuming this distribution is compared with the estimated intensities in the plot against epicentral distance in Figure 8.

38 33 Table 4. Shallow subsurface materials prevalent at places of reported effects of the 1871 earthquake. a = lava or well-consolidated sediment b = moderately consolidated sediment c = poorly consolidated sediment Place Material Place All islands Maui Cliffs a Lahaina Material b-c Oahu Lahainaluna a-b Waialua c Olowalu Waianae c Waikapu Ewa b Wailuku Honolulu b-c Makawao Punahou b Ulupalakua Kaneohe b-c Hana Molokai Hawaii Pukoo vicinity b-c Kohala Kalae vicinity a-b Waimea Lanai Kawaihae Palawai Valley a-b Kailua Hilo b-c b b a a a b a-b a a a

39 W f~ 220 NIIHAU 21 () :::;:;;::~(~\:j: ~... ::}{~\\\\\\\\\\::;::. KAUAI I ~ I OAHU vr--7-- I.\ VII o Miles o.~o ~o.1~o " "1.,, A r. 'sh j I I 'ljo' i 11~O Kilometers Roman numerals: M~ intensity in discrete-valued scale Arabic numerals: MM intensity in continuous scale 19 Figure 7. Reestimated intensity distribution of the 187~ earthquake assuming a point source.

40 10 X IX..... lj... 11\ 53 ~ 8 6,!; 4 I '.,:. Calculated distribution 1.0. i \ VII VIII J I ~ VI.. lj V IV III \ C 2l c... 2 I- Eplcentral diatances calculaged 0 assuming epicenter at 20.8 N W. II I o Epicentral distances. x. km. 300 Figure 8. Intensities of the 1871 earthquake in relation to epicentra1 distance. w U1

41 36 The estimated epicenter lies within the Molokai fracture zone (Macdonald et al., 1983), which is eybdenced both northwest of and southwest of the Hawaiian islands with atrend of about N 15 E. No other moderately large or large earthquakes are known to have originated in this vicinity, but the epicenters of several small ones have been located in this vicinity on the basis of seismographic evidence. (Bruce Turner, Pacific Tsunami Warning Center, personal communication.) Discrepancies between calculated and estimated intensities, and uncertainties in source estimation As indicate in Figure 8, the discrepancies between the calculated intensities and those estimated from the effects of the earthquakes are reduced, with above assumptions as to the source so that, except at one place, the calculated values in lie.within the ranges of uncertainty in the estimates; and, at that place, Ulupalakua (x = 58 km) the calculated value is at the upper end of the range of uncertainty. It will be noted that the intensities calculated for epicentral distances greater than 200 km, although lying well within the range of uncertainty of estimated values, are consistently greater than the estimates considered most probable, indicating that the actual rate of attenuation of intensity with distance was slightly greater than that indicated by the formula. However, if altered to fit better the intensity distribution of the 1871 earthquake, the formula would fit less well, on the average, the intensity distributions of other Hawaiian earthquakes used by Cox (1984) in its calibration. Some alternative combinations of source characteristics would result in fits almost as good as that indicated by Figures 7 and 8. The alternative characteristics include a rupture extending southwestward from the epicenter, focal depths as little as 10 km and as great as 20 km, and magnitudes as small as 6.9 or as large as 7.2. Recognizing not only that a range of source characteristics whose assumption would produce reasonably good fits between calculated and estimated intensities, but that the values of the coefficients in the formula and even its form are uncertain, the epicentrallocation of the earthquake cannot be considered to have been estimated more closely than about 60 km, its magnitude more closely than about 0.5 units, or its focal depth more closely than about 10 km. Number and intensities of aftershocks It seems reasonable to assume that: 1) The two or three aftershocks that were felt in Honolulu late at night on 20 February (Gazette, 22 February) were among those reported by Alexander (1871) as occurring on 21 February; 2) Those aftershocks and the shock or shocks felt in Honolulu on 24 February (Alexander, 1871) were among the several reported felt on Lanai by 21 February (W.M.G. in Gazette, 1 March) and among the frequent shocks felt on Molokai before 3 March (Advertiser, 4 March); and 3) The aftershock reported felt in Honolulu at 23:45 on 3 March (Advertiser, 4 March) was the same as that reported felt more severely at midnight on Molokai (Advertiser, 11 March), and reported felt at midnight on Maui and Hawaii also (Au Okoa, 9 March). If so the number of aftershocks reported felt on one or more of the isla"ds was between 4 and 6. On the one hand, because descriptions of the effects of these aftershocks were not published, it might be supposed that none of them had an intensity at any place that approached the intensity of the main shock of 19 February, and, indeed, that few of them assume that all of the aftershocks originated within about 50 miles of the main shock, and hence that, not only the aftershock of near-midnight on 3 March, but all others that were felt on more than one island had higher intensities on the islands closest to the origin area than the

42 37 islands further away. If the Oahu intensities of some were about II, their intensities on Molokai and Lanai might therefore be assumed II or IV. The average intensities of the several aftershocks, in areas in which they were reported felt, estimated from the range of possible intensities, are summarized in Table 4. Table 5. Estimated Modified MercalIi intensities of aftershocks of the 1871 earthquake. No. Date 2 or 3 Feb 20 I? Feb 24 1 Mar 3 Several Feb 2 additional to to those Mar 3 listed above Time Oahu a ) 21: ? : Average Intensities on Molokai b } Lanai b ) Maui b ) :!: to c) 1.2 to c) 3.0 :!: :!: 1.0 Notes: a) In Honolulu. b) c) At places not identified. Range of possible average intensities due to uncertainty as to place of reported observation. Supposed tsunami Apparently on the basis of reports of the earthquake in European publications, Solov'ev and Go (1975) indicated that the 1871 earthquake was accompanied by a tsunami. However, as indicated on the section on "tsunami concerns", there is no clear evidence of the occurrence of a tsunami although some correspondents stated that such evidence was looked for at Honolulu and Lahaina. Alexander (I871) stated that no "earthquake wave" was reported. Cox and Morgan (1977) concluded that the probability that a tsunami occurred is very slight, and that if one occurred it was very small.

43 38

44 39 CONCLUSIONS In conclusion, it is estimated in the study that the epicenter of the February 1871 earthquake was within 60 km of N, W, a point on the coast of Lanai, that it had a Richter magnitude of , and that it had a focal depth of km. The highest intensity of the earthquake on land is considered to have been IX in the -conventional discretestep Modified Mercalli scale on Lanai ( in the equivalent continuolls scale). Its highest probable average intensities on other islands are estimated at VIII or IX on Molokai ( in the Pukoo vicinity); vm on Maui ( at Lahaina; VII or VII on Oahu ( :-7 at Honolulu; Von Kauai (4.8 :.':. 1.5); and IV on Niihau (4.5 :.':. 1.5). - The location of the epicenter near Lanai and the experience of the highest intensity on that island seem so certain that the earthquake may appropriately be referred to as the Lanai earthquake of Among other historic Hawaiian earthquakes, only those of April 1868 and November 1975, both of which originated on the southeast coast of Hawaii, had magnitudes higher than that considered most probable for the Lanai earthquake.

45 40

46 41 ACKNOWLEDGEMENTS I am indebted to A. S. Furumoto, Hawaii Institute of Geophysics, for receipt of copies of O. A. Macdonald's unpublished review of Furumoto et al., 1973 and of Esther Mookini's translations of Hawaiian-language reports on the 1871 earthquake, to Spencer Leinweber and Glenn Mason for their information on masonry buildings in existence in Honolulu 1871 t to Linda Wiig who brought to my attention the information on the construction of buildings at Punahou School and to Esther Mookini for clarification of the meaning of some of the Hawaiianlanguage reports where I had questions as to the geophysical implications of her original transla tions. Drafts of this report or sections of it were submitted to those who contributed as recognized above to its preparation, to W.M. Adams of the Hawaii Insitute of Geophysics t and to B.W. Turner of the Pacific Tsunami Warning Center, and also to the members (other than the author) of the Task Force appointed by the Natural Hazards Group of the University of Hawaii to investigate the question of appropriate seismic-risk zoning for Oahu: Edward Berg Elmer E. Botsai Arthur N.L. Chiu Fred K. Duennebier I am particularly indebted: i) to Adams, Furumoto, and Turner for their review of an early draft and the provision of comments that led to several significant revisions including increases in the estimates of the intensity of the earthquake on Molokai and Lanai and at Lahaina, Maul; and ii) to Duennebier who reviewed a near-final draft. In spite of the revisions t the report cannot be assumed to represent the opinions of those who commented on the draft, some of whom consider that I have underestimated the intensity of the quake at places where I did not increase the estimates, and possibly even at those place.

47 42

48 43 REFERENCES Alexander, W.D., On the earthquake at Oahu, Hawaiian Islands. Am. Jour. Sci., sere 3, vol. 1, no. 6, p Alexander, M.C. and C.P. Dodge, Punahou, Univ. Calif. Press. Berg, E., E. Botsai, A. Chiu, D.C. Cox, and F. Duennebier, in prep. Seismic-Risk Zoning for Oahu, Univ. Haw. Environ. Ctr. Coffman, J.L., C.A. Von Hake, and C.W. Storer. (editors), Earthquake History of the United States. U.S. Dept. Commerce, National Oceanic and Atmospheric Admin; and U.S. Dept. Interior, Geological Survey; 208 pp. plus 50 pp. supple Cox, D.C., in press. Approximate relationship of intensity to magnitude and hypocentral distance for Hawaiian earthquakes. Univ. Haw. Environ. Ctr. Cox, D.C., in prep. Oahu Intensities of Historic Earthquakes, Univ. Haw. Environ. Ctr. Cox, D.C. and J. Morgan, Local tsunamis and possible local tsunamis in Hawaii. Hawaii Inst. Geophys., HlG 77-14, 118 pp. Eppley, R.A., Earthquake History of the United States, Part I. U.S. Coast and Geodetic Survey, 120 pp. Furumoto, A.S., Recent data for seismicity of Hawaii as regards seismic zoning. Appendix B in the City Council's Citizens' Blue Ribbon Committee on Emergency Preparedness and Response. City and County of Honolulu. Furumoto, A.S., N.N. Nielsen, and W.R. Phillips, A study of past earthquakes, isoseismic zones of intensity, and reeommended zones for structural design for Hawaii. Hawaii Inst. Geophys. HlG-73-4, 49 pp. Furumoto, A.S., L.V. Lum, N.N. Nielsen, and J.T. Yamamoto, A study of earthquake losses in the Honolulu area: Data and analysis. Report prepared for Dept. of Defense, Civil Defence Divison, State of Hawaii (204 pp.). Howell, B.F., Jr. and T.R. Schultz, Attenuation of Modified Mercali intensity with distance from the epicenter. Bull. SeismoL Soc. Amer., vol. 65, no. 1, pp Macdonald, G.A., Unpublished review of Furumoto et al., 1973 letter dated 15 September 1973 to Walter Lum, a foundation engineer who supported the publication of the Furumoto et al. (1973) report. Macdonald, G.A., A.T. Abbott, and F.L. Peterson, Volcanoes in the Sea, 2nd ed., Pres. Univ. Hawaii Press, HonolulU, 517 pp. Richter, C. F., Elementary Seismology Freeman, San Franciseo, 768 pp. Solov'ev, S.L. and Ch. N. Go, Katalog Tsunami na Zapadnom Poherezje Tixogo Oceana (Catalog of Tsunami on Western Coasts of the Pacific Ocean) Akad. Nauk SSSR, 309 pp. Wood, H.O. and F. Neumann, Modified Mercalli intensity scale of Bull. Seismol. Soc. Amer., vol. 21, no. 4, pp

49 44

50 45 APPENDIX: Modified Mercalli Intensity Scale of 1931 The Modified Mercalli scale of 1931 was developed by Wood and Neumann (1931) to rectify deficiencies in the earlier used Rossi-Forrel scale used for the estimation of earthquake intensities from commonly described earthquake effects. Wood and Neumann published both the complete version (Table A-I) and an abridged version (Table A-2). A 1956 abridged version of the MM scale (Table A-3) was developed by Richter (1958) to rectify discrepancies between the original abridged version and the complete version and to descriminate between types of masonry in estimating intensities of earthquakes from their effects on masonry structures. As is customary. roman numerals are used in this report to refer to the 12 discrete (integer-valued) steps in the conventional Modified Mercalli scale. Arabic numerals are used to refer to intensities in a continuous scale equivalent (Cox, 1984). If I is the (integer) value the intensity in a convetionally mapped "isointensity" zone, and It is the value of the intensity in the continuous scale: at the outer boundary of the isointensity zone, r = I - 0.5; near the middle of the zone, It = I; and in general, l' ::. I ::. If

51 46 Table A-I. Modified Mercalli intensity scale of 1931 * AJi.lI,t.:d :rom Si..!\~rg'> Mt rcalli CaIKaui Sfa:t:, modifi.. (! and cui1(\c=nsed. [i.f. N"t fclt - or, CX'~r:I\t rudy uliclrr esf'l'dall.y f;tvoral.l~ (ircumlitao\:e~. {'r.<ier!:t-rtain... IHI;t;"o,. :.t au.1 '.lilsi.!. th.~ which a grt!at ~hol:k i~ f<:lt: S(lmdin\l'~ hinb. :lililllal" rt'pnrkd ull"a~v or di~turb.. d; sflmt:times (Hzzim'ss or nau:il:'a t:lcl'erirnrl"\; 1'"1II1<1:Iry,.f ite area in sotnf'timcs tl't!t's. ~tr\lcturt's. liqui,ls. h...!\ic" of w:lkr, ma.y... wayd,-'ors may ~Will~, v.. ry ~lowly. l[ Felt indoors by few, especially on upper floors, pr hy ~"hsiti\'f', or nerv.lu> jlersons. Also, as in grade L bllt often more notic't'ahly: sometimes hanging objects may swing, especially wh.. n ddicatdy suspended; sometime!> trees. structure5. Ii'luids, hodies (If water, may sway, doors may swing. very slowly; sometimes birds. animals, reported uneasy or disturbed; sometimes dizziness or nallsf'a!!)(['i:rienrc,l III tit 1 ( R.F. IV J!.;' 1 [ J v ~'." \. to \'1 [ It... 1 J Felt indoors by several, Inotion usually rapid vibration. Somctimt:s not recognized to be an eartlhluake at first. Duration estimated in some rases. Vibration like that due to passing of light, or lightly 10;u1c<l trucks. or heavy trucks some distance away. Hanging objects may swing slightly. }.(o\'ements may hi' appreciable on upl'er h:vt"h of tall structures. RllCked ~tandjng motor cars slightly. Felt indoors by many, outdoors by few. Awakened few, ('specially light sh:epers. Frightened no one,!lule,s appn:hensivc frulll previous ('xllerienet'. YihratiplI likt! that due to passing \,f I"'avy, fir heavily luadtd trucks. S(;II~atioli like 1It',1\'y body striking huihlillg. or fall: :;.; (.f heavy ohj"cts inside. Rattling oe dishes, windows, duors; ~:tasswarc alld crockery dillk and c1a~h. Creaking of walls, frame. rspt"cially in the Il['per range of this. grallt'. Hanging objectjl swung, ill 11llrtlt'flHli i!l~tam t'~. Disturb('rt li'lui(l:; in "1'~11 "f"ssf b slightly. Rocked star~ding o!otnr cars noticeably. F eit indoors by practically au, outdoors by many or most: outdoors direction estimated. Awakened :nany. O( mo,1. Frightened few-~light, )(ritemt nl. a few rail outdoorll. r.ui1din~~ tremhl.. d throughput. Broke dishes. glas~wart'. III!\tI!lIl' I:xtl nt. Cracked windows-in some rase~, hut nut generally. Overturned vases, sman or unstable objects, in many instances, with o('{,:lsior.al fall. Hanging objects. doors. swing gcneral1y or collsiderahly. Kn('>rk«1 piclures ar.:ain,t walls. or swung them ont of lltace. ~)pened. or c1n,ed. doors. ~Imttt'rs. ahruptly. Pendulum clo.::ks stopped, st:uted, "r ran (;I:;t, or slow. Moved small objects, furnishings, the latter to sli~ht extent. Spilled liquids in small ;1.Inounls from wdl.lilted f.ji't'n containers. Trees. bushe'l, shaken slightly. *Wood and Neumann, (Parenthetical references to R.F. refer to the earlier used Rossi-Forel scale.)

52 47 VI [ ~l 1 VII RF, VII Felt by au, illlltlors au.1 ollll\onrs. Frightened many, cxcitement general, snm., :I\arm, many ran outdoors. Awakened all. PerSOIl$ li1adc to movt: un,;tcadily. Trees, bushes, shaken slightly to moderately. Liquid ~l't in strong moti(,il. Smail t",\ls r:\iij,:"-dlllrrh..;hafll l. ~(h()"i. ( te. Damage slight in jloorly hllilt huilding;. Fall of pla!lter ill small amount. Cracked plaster s(hl1ewh:lt, especially fine cracks chimneys in some in5tanees. Broke dishes, ~I;lssw:tre. ill co!lsi,!~rahle qu:llltity. :lh'n some windows. Fall of knick.kna,:ks, books, pictures. Overturned furni ture in many instances. Moved furnishings,.f 1lI,,,laatdy l!<,:wy kim!. Frightened ::Ill-general abrm. all fan (>lltd.. ors. S0111C, or 1ll'lIly. found it diffku!t to Hall(1. Nuticcli hy persuns dri\'in~ motnf cal'; 1'rees and bushes sh<lken moderately to strongly. \\';l\"'~ foil pow I" bkt'>. alul 1'IIIIIliug \\OIt,,1'. \\'atcr tllrhill from IlilIIt stirred up, Inl :,. :ing tn ~ollle I"xt.'tll "f "all,1,)r I~! an,l stn'am h:tllks. I~ang Ia!'t.;<' church hdl" dc, SI!~pl'n<lt,t1 ""jl~ct; ma.t.- 10 tl'livcr. "III-J Damage ne~ligible ill l,uildil1~~ of I~(l"t[ ""sigll allli "orhtrm:tiou, slight [ R.t'. tl' liu:d"rak ill \\'..tl lmilt ortlin:n)' Illlihti!1;,('s, considerable in ponrly built or badly d.. ~ig-llt~j hlliltlin~s,.i<\.. h.. ""ltses. "ld walls (especially where bill (:!) without I11 n rt:.tr), spir, s, t'te, Cracked cn::.meys to { "l1sidc:r.lble ('xtent. walls to Sf.mt: extent. Fall of plaster in ("""i~lerahle tn large amount, also ~ome stucco. Broke numerous windows, furniture tn ~(\m.. cxt! nt. Shook down loost'ne'd hrick\\'('.rk and lil('s. Broke weak chirnu<,.\ s at the w"f-lillt!' (somt'times.lal11aging roofs). Fall of cornices f rllm hl\\'ers,l1ld high hnildings. Di,IOl!~eflljric-k; and ~h.i1"'5. Overturned heavy furniture, with i!:\tn<lge from hreaking. Damage considerable til cnllrrd(~ irrigation ditches. VIII Fright general-alarm al1llroarhes panic. Disturht'ri persons dri"inj< mfitnr CMS. Tr<!e5 shaken strongly- hrilndll s, trunks. hroken uff, especially palm tr~$. Ejert~t1 ~and lind mud in ~miltl amollnts. Changes: tcmp.-.rary, permanent; in Row of springs and well~; dry wells renewed fl.}\\,; in leml"'rature of >pring.111<1 well waters. Damage slight ill ~trnctnres (hrick) hllilt especially t.. withstand t<arth-,' quakes. to Considerable in orllit1i1ry slih,tanti:ll huihlings. rarti.. l collapse: IX- J racked, tumbled down. \\'0(1(1t'1I Imust's in ~ome cases; threw out [ R.T!'. Jlilnd w311s in frame strul'ti1re~, hroke orf d"cayet! piling. Fall of walls. Cracked, broke, solid stone walls seriously. Wet ground to some ext.:nt, also ground on steep sillpes. Twisting, fall, of chimneys, columns, monuments, also factory stacks, tow,~rs. Moved conspicuously, overturned, very heavy furniture.

53 48 IX ( IX+ R.Y. ] x X [ R.F. XI Xli P':lIIic.:~Iu~ral. Cra\;ked ground conspicuously. Damage con~ideraule in (masl.nry) stnlctllr~:i huilt especially to with. stand earthqu.lkes : threw out of plumb some wood frame houses built e!'l'ecially to with f;tnnd (':lrthqllakes; great ill ~uhst:ltltiat (masonry) IHlit(lmK~, some cullapse ill large rart; or \\1,...lIr shifted f rame hllil(link~ o('f fo,,",lations. rack..,1 fr:tm.. s; serious to reservoirs; IIndt'rgronnd piple'; sometimes hrl)ken. Cra.:ked ground, C~j1t'cial\y when lopse ami w!:'i, up t ) widths of sc\'~ral inches; n,sures lip 10 a yard ill width ran parallel to l.':jnal and stream banks. Lam.\slidcs clllisidernhle f r<,m ri\'er hanks,\luf steep coasts. Shi fted s:lml amllll!ul ltllriwlltally (Ill he;lches anti nat land. 1 Changed 10:\'1:1 uf water in \\'l'lls, J Threw water on hanks of canals, lat,e$, river~, etc. Damage serious til!lams. dik\'s, I'mhankmt'nts. Severe to wdl l)llilt w(luden structures and hri<lgt:s, some destroy.:1. Dc\'elo\lt'd (bngeruus crark~ in c:.::cetll'nt hrick walls. Destroyed most ma"unry ilnd frame structures, also their follnda tions. Bt:!lt railroad rails slightly. Tore apart, or cru~!li:d ('n<lwise, \lip.: 1ine~ IJllritd in earth. Open cracks and broad wa\')' fohls in ('ement pavements ami asphalt road surfaces. Dif;turbancc$ in ground many and widt'spread, varying with ground material. Broad fissures, earth slumps, anrl land slip!; in soft, wet f:l'ound. Ejected water in largot: amullf'!t {:har~oo with sand and mild. Caused sea waves ("tidal" W:\\'~5) of :;i~nificant mal-[liitlllle, Damage severe to w"'iii-frame structures, especially near ~hnck centers, Great to t.!arns, dikes, embankments, often for long distances. Few, if :111)' (1l1i1,"llry), strllrtur('~ r!'tnail\\'(\ stillifling. Destr,,),t't! j,,,.qe well.built hridges by the wrecking of supporting piers, (Jr pi llj.rs, Aiitcted }idr!ing- woort... n hdt\ges less. Bent rail:cac raiis gn:atly, ami thru~t them endwise. Put I,ipe lil:t's bl1ried in earth compl.. tely (Jilt of st'rvire, Damage total-practically all works oi ClllI~trudion,Iatllagcd greatly or IkNtro}'\'d. Disturban('cs in ground gn;at and varir:d, IltItlWTOIIS shearing cracks. Lambli,\c:s, falls or rock of ~j~nificall[ character, ~Iumping of river "anks. etc., numerous and elden,j v,'. \Vrem:ht'd \o<'st', tore off, large Wt'" masst's. Fault slips in firm rork, with litjtahlt' horiwnta.! nlld vertical offset displact'mcnts. \Vater c1la 'I, snrt\c.. ;\11<1 IIIHIt rkrollml. Ilishlrlwll ami modified gr.:atly. Dammed lakes, prof\uct'tt waterfalls, d.. n... ctcd rivers, etc. \Vaves seen on ground surfaces (actuall) seen, prohahly, in some cases). Distorted lint's of sight and levt'1. Threw obje(;ts upward into the air.

54 49 Table A-2. Modified Mercalli Intensity Scale of 1931 (Abridged). (Wood and Neumann, 1931) I. Not felt except by a very few under especially favorable circumstances. U. Felt only by a few persons at rest, especially on upper floors of buildings. Delicately suspended objects may swing. m. Felt quite noticeably indoors, especially on upper floors of buildings, but many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration like passing of truck. Duration estimated. IV. During the day felt indoors by many, outdoors by few. At night some awakened. Dishes, windows, doors disturbed, walls made cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably. V. Felt by nearly everyone; many awakened. Some dishes, windows, etc., broken; a few instances of cracked plaster; unstable objects overturned. Disturbances of trees, poles and other tall objects sometimes noticed. Pendulum clocks may stop. VI. Felt by all; many frightened and run outdoors. Some heavy furniture moved; a few instances of fallen plaster or damaged chimneys. Damage slight. YD. Everybody runs outdoors. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable in poorly built or badly designed structures; some chimneys broken. Noticed by persons driving motor cars. vm. Damage slight in specially designed structures, considerable in ordinary substantial buildings with partial collapse; great in poorly built structures. Panel walls thrown out of frame structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned. Sand and mud ejected in small amounts. Changes in well water. Disturbed persons driving motor cars. IX. Damage considerable in specially designed structures; well designed frame structures thrown out of plumb; great in substantial buildings, with partial collapse. Buildings shifted off foundations. Ground cracked conspicuously. Underground pipes broken. X. Some well-built wooden structures destroyed; most masonry and frame structures destroyed with foundations, ground badly cracked. Rails bent. Landslides considerable from river banks and steep slopes. Shifted sand and mud. Water splashed (slopped) over banks. XI. Few, if any (masonry), structures remain standing. Bridges destroyed. Broad fissures in ground. Underground pipe lines completely out of service. Earth slumps and land slips in soft ground. Rails bent greatly. XU. Damage total. Waves seen on ground surfaces. Lines of sight and level distorted. Objects thrown upward into the air. Wood and Neumann (1930.

55 50 Table A-3. Modified Mercalli Scale of 1931, 1956 abridged version.* L Not felt. Marginal and long-period effects of large earthquakes. U. Felt by persons at rest, on upper noors, or favorably placed. m. Felt indoors. Hanging objects swing. Vibration like passing of light trucks. Duration estimated. May not be recognized as an earthquake. IV. Hanging objects swing. Vibration like passing of heavy trucks; or sensation of a jolt like a heavy ball striking the walls. Standing motor cars rock. Windows, dishes, doors rattle. Glasses clink. Crockery clashes. In the upper range of IV wooden walls and frame creak. V. Felt outdoors; direction estimated. Sleepers wakened. Liquids disturbed, some spilled. Small unstable objects displaced or upset. Doors swing, close, open. Shutters, pictures move. Pendulum clocks stop, start, change rate. VL Felt by all. Many frightened and run outdoors. Persons walk unsteadily. Windows, dishes, glassware broken. Knickknacks, books, etc., off shelves. Pictures off walls. FurnitW'e moved or overturned. Weak plaster and masonry D* cracked. Small bells ring (church, school). Trees, bushes shaken (visibly, or heard to rustle--cfr). VII. Difficult to stand. Noticed by drivers of motor cars. Hanging objects quiver. Furniture broken. Damage to masonry D, including cracks. Weak chimneys broken at roof line. Fall of plaster, loose bricks, stones, tiles, cornices (also unbraced parapets and architectural ornaments-cfr). Some cracks in masonry C. Waves on ponds; water turbid with mud. Small slides and caving in along sand or gravel banks. Large bells ring. Concrete irrigation ditches damaged. vm. Steering of motor cars affected. Damage to masonry C; partial collapse. Some damage to masonry B; none to masonry A. Fall of stucco and some masonry walls. Twisting, fall of chimneys, factory stacks, monuments, towers, elevated tanks. Frame houses moved on foundations if not bolted down; loose panel walls thrown out. Decayed piling broken off. Branches broken from trees. Changes in now or temperature of springs and wells. Cracks in wet ground and on steep slopes. IX. General panic. Masonry D destroyed; masonry C heavily damaged, sometimes with complete collapse; masonry B seriously damaged. (General damage to foundations CFR). Frame structures, if not bolted, shifted off foundations. Frames racked. Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in ground. In alluviated areas sand and mud ejected, earthquake fountains, sand craters. X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly. XI. XU. Rails bent greatly. Underground pipelines completely out of service. Damage nearly total. Large rock masses displaced. Lines of sight and level distorted. Objects thrown into the air. Masonry types: A. Good workmanship, mortar, and design; reinforced, especially laterally, and bound together by using steel, concrete, etc.; designed to resist lateral forces. B. Good workmanship and mortar; reinforced, but not designed in detail to resist lateral forces. C. Ordinary workmanship and mortar; no extreme weaknesses like failing to tie in at corners, but neither reinforced nor designed against horizontal forces. D. Weak materials, such as adobe; poor mortar; low standards of workmanship; weak horizontally. *Richter (1958) (CFR in annotations)