Treasure Island. Tsunami Open House. Tsunami Education

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1 Treasure Island Tsunami Education Tsunami Open House Join the San Francisco Department of Emergency Management (SFDEM) and Treasure Island Development Authority (TIDA) to learn about Treasure Island s tsunami risks, public alert and warning, and how to protect your family, friends, and community through awareness and preparedness. This event will include informational posters and opportunities to engage SFDEM, State of California Office of Emergency Services (CalOES) and TIDA staff. May 26, :30-8:00 pm Ship Shape Community Center, 850 Avenue I, Bldg 497, Treasure Island, SF Who s invited: All Treasure Island community members Sfdem.org megan.stephenson@sfgov.org Brought to you by the San Francisco Department of Emergency Management

2 Treasure Island Tsunami Open House Thanks for joining us at the open house. Below is some helpful information on tsunamis from the San Francisco Department of Emergency Management. Frequently Asked Questions Q: What is a tsunami and can it happen here? A: A tsunami is a series of ocean waves caused by a displacement of the sea floor, typically caused by a large earthquake or by a landslide into or under the water surface. Tsunamis may cause dangerous coastal flooding with strong currents that may last for many hours. Tsunamis are a low probability event for San Francisco but can have severe consequences. This why we prepare for them. A distant source tsunami with 4 to 15 hours of warning is a more likely scenario than near source tsunami with less than 15 minutes of warning. Q: How can I prepare for a tsunami? A: Prepare yourself by gathering supplies, planning ahead, and getting connected with your community. Pack a go-bag and store it somewhere quickly accessible. Your bag should have things like water, extra clothes, and first aid kit. Visit for more information. When you have to act fast, having a plan that you ve practiced is the key. Start a plan by visiting Brought to you by the San Francisco Department of Emergency Management

3 Get to know your neighbors and look out for each other now. Find out who can help and who needs help in an emergency. Consider joining San Francisco s Neighborhood Emergency Response Team (NERT) by visiting Q: How do I know if a tsunami is on the way and what do I do? A: Know the warning signs: Strong ground shaking, a loud ocean roar, or the water receding are all nature s warnings. If you re by the water move inland and higher ground immediately. If there is time (a distant source tsunami) we will send out alerts and instructions. AlertSF is one way the City will send alerts. Sign up by texting the word AlertSF to the number or by visiting Another way is Outdoor Public Warning System is designed to alert residents and visitors of San Francisco about possible danger. Q: What will the City do in the event of a tsunami? A: Emergency responders will send alerts and help facilitate evacuations if time and safety permits. If you can self-evacuate and can help someone else please do so. If you need or know someone that needs assistance call Q: What does this mean for Treasure Island? A: Moving away from a tsunami on Treasure Island means driving on to the Bay Bridge towards San Francisco. The Oakland touchdown-area of the bridge is in the tsunami flood zone. If you selfevacuate using your own vehicle please pick up your neighbors. Carpooling is essential since there is limited vehicle access to the Bay Bridge. Q: Can I walk to Yerba Buena Island? A: Yerba Buena Island offers sufficient high ground, however, there currently is no pedestrian walkway from Treasure Island. Walking to Yerba Buena Island means traveling on the same road being used by vehicles for evacuation. In the future, a bicycle path will connect Treasure Island to the eastern span of the Bay Bridge. A pedestrian walkway to Yerba Buena Island will also be established. Both may offer a safer alternative to walking on the roadway. Get Connected Connect to text alerts on ALERTSF, by texting to the word alertsf with no quotes and case doesn t matter. Check out SF72.ORG for helpful preparedness information. Call 911 for help for any emergency. Brought to you by the San Francisco Department of Emergency Management

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8 IF YOU FEEL A STRONG EARTHQUAKE WHILE NEAR THE COAST: 1. PROTECT yourself during the earthquake 1 If indoors, DROP under a sturdy table or object, COVER your head and neck and HOLD ON. If outdoors, move to a clear area if you can safely do so - away from trees, beach cliffs, signs and other hazards - and drop* to the ground. * If you have mobility impairments that prevent you from getting up on your own, do not drop to the ground but do cover your head and neck and hold on. 2. MOVE to High Ground As soon as it is safe to move, go to higher ground. DO NOT WAIT for an official tsunami warning. Avoid downed power lines and weakened overpasses. If you are outside of a tsunami hazard zone, stay where you are. 3. STAY There DROP DROP! Remain on high ground. Waves from a tsunami may arrive for eight hours or longer. 2 COVER COVER! Return to the coast only when officials have announced that it is safe to do so. 3 HOLD ON HOLD ON! THINGS YOU SHOULD KNOW ABOUT TSUNAMIS A tsunami is a series of waves or surges most commonly caused by an earthquake beneath the sea floor. An unusual lowering of ocean water, exposing the sea floor, is a warning of a tsunami or other large wave. This draw back means the water will surge back strongly. Beaches, lagoons, bays, estuaries, tidal flats and river mouths are the most dangerous places to be. It is rare for a tsunami to penetrate more than a mile inland. Tsunami waves are unlike normal coastal waves. Tsunamis are more like a river in flood or a sloping mountain of water and filled with debris. Tsunamis cannot be surfed. They have no face for a surfboard to dig into and are usually filled with debris. Large tsunamis may reach heights of twenty to fifty feet along the coast and even higher in a few locales. The first tsunami surge is not the highest and the largest surge may occur hours after the first wave. It is not possible to predict how many surges or how much time will elapse between waves be for a particular tsunami. The entire California Coast is vulnerable to tsunamis. The Crescent City Harbor on California s North Coast suffered significant tsunami damage as recently as A dozen people were killed in California following the 1964 Alaska earthquake. ADDITIONAL RESOURCES: About tsunamis: Identifying natural hazards in your neighborhood Preparing for earthquakes and tsunamis The California Geological Survey Or contact your county Office of Emergency Services. Prepared by: California Emergency Management Agency Earthquake and Tsunami Program 3650 Schriever Avenue, Mather, CA (916) Concept and partial text from the Redwood Coast Tsunami Work Group. This document was prepared under a grant from FEMA s Grant Program Directorate, U.S. Department of Homeland Security. Points of view or opinions expressed in this document are those of the authors and do not necessarily represent the official position or policies of FEMA s Grant Programs Directorate or the U.S. Department of Homeland Security. 7_09 How to Survive a Tsunami Protect yourself during the earthquake Move to high ground or inland as soon as you can Stay there Prepared by:

9 TWO WAYS TO FIND OUT IF A TSUNAMI MAY BE COMING 1. NATURAL WARNING Strong ground shaking, a loud ocean roar, or the water receding unusually far exposing the sea floor are all nature s warnings that a tsunami may be coming. If you observe any of these warning signs, immediately go to higher ground or inland. A tsunami may arrive within minutes and may last for eight hours or longer. Stay away from coastal areas until officials announce that it is safe to return. WHEN SHOULD I EVACUATE? Evacuation should not be automatic. Before evacuating you should determine if you are in a hazard zone and consider possible hazards that may exist along your evacuation route. How you prepare will affect how you recover. And being prepared for earthquakes and tsunamis prepares you for all kinds of disasters. Know if you live, work, or play in a tsunami hazard zone. Learn what the recommended tsunami evacuation routes are in your city, county and region. Identify safety zone(s) near you, and decide on your primary and secondary evacuation routes. COUNT how long the earthquake lasts. If you feel more than 20 seconds of very strong ground shaking and are in a tsunami hazard zone, evacuate as soon as it is safe to do so. If you are on the beach or in a harbor and feel an earthquake no matter how small immediately move inland or to high ground. GO ON FOOT. Roads and bridges may be damaged. Avoid downed power lines. If evacuation is impossible, go to the third or higher floor of a sturdy building or climb a tree. This should only be used as a last resort. 2. OFFICIAL WARNING You may hear that a Tsunami Warning has been issued. Tsunami Warnings might come via radio, television, telephone, text message, door-to-door contact by emergency responders, NOAA weather radios, or in some cases by outdoor sirens. Move away from the beach and seek more information on local radio or television stations. Follow the directions of emergency personnel who may request you to evacuate beaches and low-lying coastal areas. Use your phone only for life-threatening emergencies. PREPARE NOW If you hear that a tsunami warning has been issued but did not feel an earthquake, get more information. Listen to the radio, television or other information sources and follow the instructions of emergency personnel. If you are outside of a tsunami hazard zone, take no action. You are safer staying where you are. Know if you live, work, or play in a tsunami hazard zone. If you live or work in a tsunami hazard zone get a NOAA weather radio with the public alert feature for your home and office. It will alert you even if turned off. Assemble a small evacuation kit with essential documents, medications, a flashlight, a portable NOAA weather radio and batteries, water, snacks and warm clothes. Include a silver space blanket in your kit it can be used to signal your location to air search teams. Keep your evacuation kit by the door so you can grab & go. Walk your route consider what you would do at night or in stormy weather. Make a reunification plan with your loved ones. Decide when and where you will meet if you are separated, and what out of state relative or friend you will call if it is not possible to meet at your pre designated reunification spot. Discuss plans with family, coworkers and neighbors. Make plans for how to address any functional needs or disabilities you might have. If you need help evacuating, prearrange assistance from neighbors including transport of mobility devices and durable medical equipment. If you are mobility impaired, account for the extra time that you may need. Decide on the best strategy for protecting your pets. Prepare to be on your own for several days or longer. Consider joining your Community Emergency Response Team ( WHERE SHOULD I GO? Natural and official warnings are equally important. Respond to whichever comes first. All California coastal counties have tsunami hazard guidance maps and are in the process of posting tsunami hazard zone signs. These signs and maps will show you what areas are safe and what areas may be at risk. Use them to guide you to a safe area. If no maps or signs are available, go to an area 100 feet above sea level or two miles inland, away from the coast. If you cannot get this far, go as high as possible. Every foot inland or upwards can make a difference.

10 CALIFORNIA GEOLOGICAL SURVEY NOTE 55 A tsunami is a wave, or series of waves, generated by an earthquake, landslide, volcanic eruption, or even large meteor hitting the ocean (The Japanese word tsu means harbor ; nami means wave ). What typically happens is a large, submarine earthquake (magnitude 8 or higher) creates a significant upward movement of the sea floor resulting in a rise or mounding of water at the ocean surface. This mound of water moves away from this center in all directions as a tsunami. A tsunami can travel across the open ocean at about 500-miles per hour, the speed of a jet airliner. As the wave approaches land and as the ocean shallows, the wave slows down to about 30 miles-per-hour and grows significantly in height (amplitude). Although most people think a tsunami looks like a tall breaking wave, like the wave shown in the image of Japanese artwork (below left), it actually resembles a flood or surge, like that shown in the picture below right from the 2004 Indian Ocean Tsunami (images courtesy of NOAA). Earthquake! If you feel an earthquake or become aware that one has occurred, do not stay in an area that is susceptible to a tsunami.move to high ground! Even a large earthquake thousands of miles away can trigger a tsunami that can cross an ocean hours later. Watch the tides! An approaching tsunami is sometimes proceeded by a rise or fall of water levels or strange bubbling in the tidal areas. If this occurs, it could be a sign that a tsunami is on its way. Head for higher ground! Stay tuned in! Television, radio, and internet resources are good places to find out whether a tsunami is heading your way. Emergency evacuation procedures will be relayed and should be followed as soon as possible. The Story of 10-Year-Old Tilly Smith When you learn about the warning signs of a tsunami, it might not only save your life it might help save the lives of your family and others. Tsunamis can cause great loss of life and damage to property, as we learned in the 2004 Indian Ocean Tsunami which killed over 230,000 people in eleven different countries. The key to surviving a tsunami is to know what the warning signs are, and know what to do and where to go if you think a tsunami is about to strike. On December 26 th, 2004, while vacationing with her family on a beach in Thailand, Tilly Smith, a 10-year old girl from Great Britain, noticed that the tide was rushing out and the ocean was strangely bubbling (similar to the picture shown below; courtesy NOAA). Tilly, who had studied tsunamis in a geography class two weeks earlier, quickly realized they were in danger. She warned her mother that it could be a tsunami and that they had to get off the beach immediately. Her parents alerted the others at the beach, which was quickly evacuated. The tsunami hit a few minutes later, but no one on the beach was killed or seriously injured. Pictures of evacuation drill in Samoa, California, courtesy Lori Dengler (Humboldt State University) and Jim Goltz (California Emergency Management Agency). Although the 2004 Indian Ocean Tsunami claimed the lives of over 200,000 people, Tilly Smith likely saved the lives of her family and over 100 other people on that beach. If you remember the warning signs, you too can become a tsunami hero. California Department of Conservation, Reproduction of this CGS Note for classroom or public education purposes is encouraged and does not require written permission. Please cite California Geological Survey as source. The Department of Conservation makes no warranties as to the suitability of this product for any particular purpose.

11 PAGE 2 Have tsunamis occurred in California? More than eighty tsunamis have been observed or recorded in California in historic times. Fortunately, almost all of these were small and did little or no damage. Though damaging tsunamis have occurred infrequently in California, they are a possibility that must be considered in coastal communities. There are two sources for California tsunamis, based on distance and warning time: Local sources Local tsunami sources, like large offshore faults and massive submarine landslides, can put adjacent coastal communities at the greatest risk of a tsunami because the public must respond quickly with little or no official guidance. The Cascadia Subduction Zone is an example of a local tsunami source that could threaten northern California. Stretching from Cape Mendocino, California, to Vancouver Island, British Columbia, this 700-mile long submarine fault system forms the crustal plate boundary where the offshore Gorda and Juan de Fuca plates dive, or subduct, beneath the North American plate. Examples of local tsunamis that have impacted California include: January 26, An earthquake estimated at a magnitude 9 ruptured the entire length of the Cascadia Subduction Zone, likely causing a 50- foot tsunami in parts of northern California. Though there were no local written accounts, scientists have reconstructed the event based on geologic evidence and oral histories from the Native American people in the area, and determined the exact date and time from Japanese documents that describe the effects of a large tsunami that hit the coast of Japan later that same day. December 21, 1812 A tsunami struck the Santa Barbara and Ventura coastline shortly after a large earthquake was felt in the area. Though reports of the size of this tsunami have been debated, the event was large enough to inundate lowland areas and cause damage to nearby ships. One theory is that the tsunami was caused by a nearby submarine landslide triggered by the earthquake. Distant sources A tsunami caused by a very large earthquake elsewhere on the Pacific Rim could reach the California coast many (4 to 15) hours after the earthquake. The Alaska-Aleutians Subduction Zone is an example of a distant source that has caused destructive tsunamis in California. Notable distant tsunamis that have impacted California include: April 1, 1946 A magnitude 8.8 earthquake in the Aleutian Islands generated a tsunami that caused damage along the coast of California, including flooding over 1000-feet inland in Half Moon Bay. March 28, 1964 Twelve people were killed in California when a tsunami was generated by a magnitude 9.2 earthquake off the coast of Alaska. A surge approximately 20-feet high flooded 29 city blocks of Crescent City. March 11, 2011 A magnitude 9.0 earthquake in the Tohoku region of Japan produced a moderate amplitude tsunami in California. Although it did not generate significant flooding in California, strong tsunami currents caused one death and over $50-million in damages to 27 harbors statewide, with the most significant damage occurring in Crescent City and Santa Cruz (pictured below; courtesy Santa Cruz Port District). What is your risk? The California Geological Survey (CGS) provides geologic and seismic expertise to the public, other State government offices, such as the California Emergency Management Agency (CalEMA), and local government agencies (cities and counties). With funding from the National Tsunami Hazard Mitigation Program, CGS worked closely with CalEMA and the Tsunami Research Center at the University of Southern California to produce statewide tsunami inundation maps for California (an example from the Santa Barbara area is shown to the right). These maps are used by coastal communities to produce emergency evacuation plans. You can check to see if you live, work, or vacation in one of these potential tsunami inundation areas. Visit the CGS tsunami website below to view these maps, and to learn more about what YOU can do to prepare you and your family for a tsunami. Related Websites California Geological Survey tsunami page - California Emergency Management Agency and myhazards.calema.ca.gov Tsunami Research Center at University of Southern California - National Tsunami Hazard Mitigation Program - nthmp.tsunami.gov/ Redwood Coast Tsunami Working Group - National Ocean and Atmospheric Administration Tsunami page THE RESOURCES AGENCY JOHN LAIRD SECRETARY FOR NATURAL RESOURCES STATE OF CALIFORNIA EDMUND G. BROWN, JR. GOVERNOR DEPARTMENT OF CONSERVATION MARK NECHODOM DIRECTOR

12 Notable Historical Tsunamis in the San Francisco Bay Area Run-up amplitude, in feet, above normal tide conditions OBS = observed tsunami activity NR = No damage or severe conditions reported - Distant Source - Tsunamis without felt earthquakes - Local Source - Earthquake and tsunami together

13 Tsunami Source Scenario Model Results for the San Francisco Bay Area Near shore tsunami heights (flow depths) for both local and distant source scenarios, in FEET above Mean Sea Level. NOTE: The projections do not include any adjustments for ambient conditions, such as storm surge and tidal fluctuations, and model error (it is very important to note this difference, as those numbers can increase the projected water height during an event).

14 Notable Historical Tsunamis in the City of San Francisco Run-up amplitude, in feet, above normal tide conditions OBS = observed tsunami activity NR = No damage or severe conditions reported - Distant Source - Tsunamis without felt earthquakes - Local Source - Earthquake and tsunami together

15 Tsunami Source Scenario Model Results for the City of San Francisco Near shore tsunami heights (flow depths) for both local and distant source scenarios, in FEET above Mean Sea Level. NOTE: The projections do not include any adjustments for ambient conditions, such as storm surge and tidal fluctuations, and model error (it is very important to note this difference, as those numbers can increase the projected water height during an event).

16 California Emergency Management Agency California Geological Survey University of Southern California State of California City and County of San Francisco Tsunami Inundation Map for Emergency Planning San Francisco '0"W '30"W 37 45'0"N W ES T NC A ND FR Map O AK LA SA N PO IN T B IS C O O N IT A NO R TH 37 45'0"N '0"W TSUNAMI INUNDATION MAP FOR EMERGENCY PLANNING State of California ~ City and County of San Francisco The bathymetric/topographic data that were used in the tsunami models consist of a series of nested grids. Near-shore grids with a 3 arc-second (75- to 90-meters) resolution or higher, were adjusted to Mean High Water sea-level conditions, representing a conservative sea level for the intended use of the tsunami modeling and mapping. SCALE 1:36,000 The accuracy of the inundation line shown on these maps is subject to limitations in the accuracy and completeness of available terrain and tsunami source information, and the current understanding of tsunami generation and propagation phenomena as expressed in the models. Thus, although an attempt has been made to identify a credible upper bound to inundation at any location along the coastline, it remains possible that actual inundation could be greater in a major tsunami event. This map does not represent inundation from a single scenario event. It was created by combining inundation results for an ensemble of source events affecting a given region (Table 1). For this reason, all of the inundation region in a particular area will not likely be inundated during a single tsunami event Lander, J.F., Lockridge, P.A., and Kozuch, M.J., 1993, Tsunamis Affecting the West Coast of the United States : National Geophysical Data Center Key to Geophysical Record Documentation No. 29, NOAA, NESDIS, NGDC, 242 p. National Atmospheric and Oceanic Administration (NOAA), 2004, Interferometric Synthetic Aperture Radar (IfSAR) Digital Elevation Models from GeoSAR platform (EarthData): 3-meter resolution data. Titov, V.V., and Synolakis, C.E., 1998, Numerical modeling of tidal wave runup: Journal of Waterways, Port, Coastal and Ocean Engineering, ASCE, 124 (4), pp U.S. Geological Survey, 1993, Digital Elevation Models: National Mapping Program, Technical Instructions, Data Users Guide 5, 48 p Tsunami Inundation Area 1.5 The inundation map has been compiled with best currently available scientific information. The inundation line represents the maximum considered tsunami runup from a number of extreme, yet realistic, tsunami sources. Tsunamis are rare events; due to a lack of known occurrences in the historical record, this map includes no information about the probability of any tsunami affecting any area within a specific period of time. Miles 1, ,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 Please refer to the following websites for additional information on the construction and/or intended use of the tsunami inundation map: Feet Kilometers Table 1: Tsunami sources modeled for the City and County of San Francisco coastline. Sources (M = moment magnitude used in modeled event) Local Sources References: Intermap Technologies, Inc., 2003, Intermap product handbook and quick start guide: Intermap NETmap document on 5-meter resolution data, 112 p Tsunami Inundation Line This tsunami inundation map was prepared to assist cities and counties in identifying their tsunami hazard. It is intended for local jurisdictional, coastal evacuation planning uses only. This map, and the information presented herein, is not a legal document and does not meet disclosure requirements for real estate transactions nor for any other regulatory purpose. June 15, 2009 In order to enhance the result from the 75- to 90-meter inundation grid data, a method was developed utilizing higher-resolution digital topographic data (3- to 10-meters resolution) that better defines the location of the maximum inundation line (U.S. Geological Survey, 1993; Intermap, 2003; NOAA, 2004). The location of the enhanced inundation line was determined by using digital imagery and terrain data on a GIS platform with consideration given to historic inundation information (Lander, et al., 1993). This information was verified, where possible, by field work coordinated with local county personnel. MAP EPLANATION PURPOSE OF THIS MAP SAN FRANCISCO A suite of tsunami source events was selected for modeling, representing realistic local and distant earthquakes and hypothetical extreme undersea, near-shore landslides (Table 1). Local tsunami sources that were considered include offshore reverse-thrust faults, restraining bends on strike-slip fault zones and large submarine landslides capable of significant seafloor displacement and tsunami generation. Distant tsunami sources that were considered include great subduction zone events that are known to have occurred historically (1960 Chile and 1964 Alaska earthquakes) and others which can occur around the Pacific Ocean Ring of Fire. Titov, V.V., and Gonzalez, F.I., 1997, Implementation and Testing of the Method of Tsunami Splitting (MOST): NOAA Technical Memorandum ERL PMEL 112, 11 p. N '30"W METHOD OF PREPARATION Initial tsunami modeling was performed by the University of Southern California (USC) Tsunami Research Center funded through the California Emergency Management Agency (CalEMA) by the National Tsunami Hazard Mitigation Program. The tsunami modeling process utilized the MOST (Method of Splitting Tsunamis) computational program (Version 0), which allows for wave evolution over a variable bathymetry and topography used for the inundation mapping (Titov and Gonzalez, 1997; Titov and Synolakis, 1998). HU SA N FR A TE R S NC IS C O PO IN T SO U TH Area Distant Sources Point Reyes Thrust Fault Rodgers Creek-Hayward Faults San Gregorio Fault Cascadia Subduction Zone-full rupture (M9.0) Central Aleutians Subduction Zone #1 (M8.9) Central Aleutians Subduction Zone #2 (M8.9) Central Aleutians Subduction Zone #3 (M9.2) Chile North Subduction Zone (M9.4) 1960 Chile Earthquake (M9.3) 1964 Alaska Earthquake (M9.2) Japan Subduction Zone #2 (M8.8) Kuril Islands Subduction Zone #2 (M8.8) Kuril Islands Subduction Zone #3 (M8.8) Kuril Islands Subduction Zone #4 (M8.8) Marianas Subduction Zone (M8.6) Area of Inundation Map Coverage and Sources Used San Francisco Bay State of California Emergency Management Agency, Earthquake and Tsunami Program: 51BA F005E8D80?OpenDocument University of Southern California Tsunami Research Center: State of California Geological Survey Tsunami Information: National Oceanic and Atmospheric Agency Center for Tsunami Research (MOST model): MAP BASE Topographic base maps prepared by U.S. Geological Survey as part of the 7.5-minute Quadrangle Map Series (originally 1:24,000 scale). Tsunami inundation line boundaries may reflect updated digital orthophotographic and topographic data that can differ significantly from contours shown on the base map. DISCLAIMER The California Emergency Management Agency (CalEMA), the University of Southern California (USC), and the California Geological Survey (CGS) make no representation or warranties regarding the accuracy of this inundation map nor the data from which the map was derived. Neither the State of California nor USC shall be liable under any circumstances for any direct, indirect, special, incidental or consequential damages with respect to any claim by any user or any third party on account of or arising from the use of this map.

17 How should boat owners PREPARE for tsunamis? Prior to arrival of the March 11, 2011 tsunami along the California coast, many boat owners took their boats offshore without adequate supplies or knowledge of how long they would need to stay offshore. As a result, boaters tried to re-enter harbors too early, while dangerous tsunami conditions still existed. They put themselves and harbor personnel at risk of injury and death. Before you plan to leave safe harbor, consider the following: Talk to the harbor master or related officials to learn about your harbor s tsunami safety protocols. Sign up to receive tsunami alerts from NOAA and emergency calls from your harbor master or community emergency services office. Know weather conditions out on the ocean. Know how long it takes your boat to get to deep water. The 100-fathom line is the NOAA recommendation. Have adequate supplies (water, shelter, food) and fuel to remain at sea for 24 hrs or more. Have a family plan for tsunamis in place so you know your family will be safe. If you do not have these essential preparedness items covered, DO NOT attempt to take your boat offshore. Secure your boat to the dock and leave the dock area before the tsunami arrives. Boat attempting to leave Crescent City Harbor during the March 11, 2011 tsunami Other resources for tsunami information in California State of California Tsunami Program (California Geological Survey website): California Office of Emergency Services Earthquake and Tsunami Program: ages/tsunami-preparedness.aspx NOAA National Weather Service Weather Forecast Offices: Eureka SF Bay/Monterey Los Angeles/Oxnard San Diego - Federal Emergency Management Agency: Redwood Coast Tsunami Work Group/ Humboldt State University: California Harbor Master and Port Captain Association : Marine Recreation Association: marina.org CA Boating Safety Officers Association: cbsoa.org What BOATERS should know The March 11, 2011 tsunami in Santa Cruz Harbor Crescent City Harbor after the March 11, 2011 tsunami Prepared by: Funded by:

18 What is a TSUNAMI? A tsunami is a series of water surges usually caused by an earthquake beneath the sea floor. These can cause strong, dangerous currents inside harbors and bays. TSUNAMIS CAN TRICK YOU! The first surge may not be the largest. It is not unusual for tsunami surges to continue for 12 hours and in some cases much longer. Just when you think it is all over, another very large surge may come. 2 Ways to Know if a Tsunami is Coming: *Natural Warnings* On shore: GROUND SHAKING, a LOUD OCEAN ROAR, or the WATER RECEDING UNUSUALLY FAR exposing the sea floor. On the water: You may still feel the earthquake through the hull of your boat. You could see a rapid and extreme shift to an outgoing tide. *Official Warnings* On shore: You may hear an outdoor siren or announcements from airplanes. Determine how you can receive a call from your harbor master or community emergency services office, or sign up for NOAA alert notifications (see back). On the water: You may receive a Tsunami Advisory or Warning on your marine VHF radio s CHANNEL 16 or weather frequency (as long as your radio has the Alert feature). Natural Warning The natural warnings described to the left indicate that a tsunami could arrive within minutes. Your response depends on where you are: If you are on land or tied up at the dock: Leave your boat and go to high ground on foot as soon as possible. You don t have time to save your boat in this situation and could die if you try to do so. If you are on the water but very near shore: If you can beach or dock your boat and get to high ground on foot within ten minutes of a Natural Warning, then this is your best chance. If that is not possible, head to deep water as quickly as possible. If you are in deep water or very close to deep water: If you are already in 100 fathoms of water (600 feet) then you are safe from tsunamis. If you are in deep water but not quite 100 fathoms, head todeeper water. There are a number of TSUNAMI HAZARDS that could affect boats/boaters: Sudden water-level fluctuations Boats that hit bottom as water level drops Strong and unpredictable currents Tsunami bores and amplified waves Eddies/whirlpools Drag on large keeled boats Collision with other boats, docks, and debris Official Warning The National Weather Service, provides tsunami information for California boaters: ADVISORIES Peak tsunami wave heights between 1-3 feet are expected, indicating strong and dangerous currents can be produced inharbors. WARNINGS Tsunami wave heights could exceed 3 feet, indicating very strong, dangerous currents and inundation of dry land is anticipated Should you take your boat OFFSHORE? The answer tothis question depends on: 1) The SIZE of the tsunami. 2) How much TIME you have. 3) The PREPAREDNESS of the boat and its captain (see back). 4) The WEATHER at sea could be as dangerous as the tsunami itself. Your harbor master or port captain may provide the best advice. For most harbors in California, it is safer to keep your boat docked during a tsunami because most tsunamis are relatively small. On the rare occasion when a larger tsunami is expected (Warning level), the boat owner may consider taking their boat offshore using the criteria above. Do not go offshore unless you are very sure that you can get to 100 fathoms (600 feet) before the tsunami arrives. Note for trailer boat owners: Expect congested boat ramps and remember that you have to get your boat to the trailer, out of the water, and out of the tsunami zone before the tsunami arrives