Research on Prevention of Secondary Damage by Tracing. Drifting Paths of Floating Debris Originated from the Great East. Japan Earthquake (K122110)

Transcription

1 FY2012 Research Project Subsidized by the Environment Research and Technology Development Fund, Ministry of the Environment, Government of Japan Research Report Research on Prevention of Secondary Damage by Tracing Drifting Paths of Floating Debris Originated from the Great East Japan Earthquake (K122110) March 2013 Principal researcher: Haruo MATSUMURA (Professor, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Members of research project: Masaru TANAKA (Director, Sustainability Research Institute, Tottori University of Environmental Studies) Tomomichi KOBAYASHI (Professor, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Tetsuji ARATA (Associate Professor, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Shin SATO (Lecturer, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Koki NISHIZAWA (Lecturer, Department of Business Administration, Faculty of Business Administration, Tottori University of Environmental Studies) Sang-Yul KIM (Specially Appointed Assistant Professor, Division of Built Environment, Graduate School of Engineering, Hokkaido University)

2 Name of subsidized project: FY2012 Research Project Subsidized by the Environment Research and Technology Development Fund Competent ministry: Ministry of the Environment Amount of government subsidy: 19,177,000 yen Title of research project: Research on Prevention of Secondary Disaster by Investigation of Drift Routes of Marine Debris Generated from the Tsunami Following the Great East Japan Earthquake Term of project: July 2, 2012 March 31, 2013 Principal researcher: Haruo MATSUMURA (Professor, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Members of research project: Masaru TANAKA (Director, Sustainability Research Institute, Tottori University of Environmental Studies) Tomomichi KOBAYASHI (Professor, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Tetsuji ARATA (Associate Professor, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Shin SATO (Lecturer, Department of Environmental studies, Faculty of Environmental Studies, Tottori University of Environmental Studies) Koki NISHIZAWA (Lecturer, Department of Business Administration, Faculty of Business Administration, Tottori University of Environmental Studies) Sang-Yul KIM (Specially Appointed Assistant Professor, Division of Built Environment, Graduate School of Engineering, Hokkaido University)

3 Contents Chapter 1 Outline of Research Research Objectives Research Methodology Results and Discussion Contribution to Environment Policy Feasibility of Results of Research Conclusions Research Plan... 6 Chapter 2 Investigation of Drift Route Research Objectives Research Methodology Results of the Second Release Experiment Results of the Third Release Experiment Results of the Fourth Release Experiment Summary Chapter 3 Investigation of Damage Caused by Marine Debris and Source of Debris Generation Introduction Interview Survey to Gather Data on Actual Secondary Disaster in Entire Hokkaido Caused by Marine Debris from the March 11, 2011 Tsunami Interview Survey with the Kushiro General Subprefectural Bureau Consideration on Secondary Disaster Expected to Occur Based on Field Survey of Drifted Debris in Hokkaido Summary Chapter 4 Proposal of Multifaceted Utilization of Marine Debris Information Utilization of Marine Debris Information Necessity of Provision of Information on Marine Debris and Drifted Debris from the March 11, 2011 Tsunami Results of Drift Route Prediction of Marine Debris from the March 11, 2011 Tsunami Secondary Disaster Caused by the Tsunami-Generated Marine Debris Future Problems to Be Addressed Chapter 5 Discussion on Method to Estimate Amount of Marine Debris Generated Estimation Method Based on Floor Area of Disaster-Stricken Buildings Estimation Method Based on the Number of Damaged Buildings Verification of Methods to Estimate Amount of Disaster Waste Generated Future Tasks to Be Addressed... 43

4 Research Presentation, etc Illustration of Research Outline... 46

5 Report of the Research Project Subsidized by the Environment Research and Technology Development Fund Chapter 1 Outline of Research - Title of research project and project number: Research on Prevention of Secondary Disaster by Investigation of Drift Routes of Marine Debris Generated from the Tsunami Following the Great East Japan Earthquake (K122110) - Amount of government subsidy allocated: JPY19,177,000 (Japanese Yen) - Term of project: 2012 to Fiscal year of project: Principal researcher: Haruo MATSUMURA (Tottori University of Environmental Studies) - Members of research project: Masaru TANAKA (Tottori University of Environmental Studies) Tomomichi KOBAYASHI (Tottori University of Environmental Studies) Tetsuji ARATA (Tottori University of Environmental Studies) Shin SATO (Tottori University of Environmental Studies) Koki NISHIZAWA (Tottori University of Environmental Studies) Sang-Yul KIM (Hokkaido University) 1. Research Objectives Among the various types of debris generated from the tsunami following the Great East Japan Earthquake, the marine debris washed ashore in littoral regions has been posing problems in ship navigation as it blocks harbors and also is extensively and adversely affecting industrial activities and life environment of coastal areas. Since FY2009, the Tottori University of Environmental Studies has conducted a study on reduction of generation of marine debris and its recovery and disposal in the Sea of Japan coasts. As an extension of this study, we have undertaken a two-year study on marine debris generated from the tsunami following the Great East Japan Earthquake. In this research, we aimed to track the drift routes of marine debris generated from the tsunami using simulated debris to which transmitters were attached and to investigate possible damage on the basis of past disasters to formulate measures to minimize the possible secondary damage. Moreover, we aimed to propose an effective way to deliver information to stakeholders and specific domestic and oversea organizations for their use, thus contributing to prevention of possible secondary disasters in the future. 2. Research Methodology To determine the different drift routes by type of debris, we used floating-type simulated debris, standard-type simulated debris, and subsurface-type simulated debris that were released 1

6 simultaneously at the same spot in the vicinity of the disaster-stricken area. The same experiment was simultaneously conducted at three different points to analyze the differences between ocean areas. With regard to the investigation of damage caused by the debris and the sources of marine debris generated, we actually visited areas where the arrival of marine debris generated from the tsunami following the earthquake on March 11, 2011 had already been confirmed by the mass media. We exchanged opinions with the staff of the Hokkaido government and the relevant local municipalities with the aim to gather information on the situation such as when the debris reached, debris composition, and currently adopted disposal methods. We then discussed future countermeasures. In addition, we have started to post the information about the transmitter location collected in this investigation on the university s website and also started to discuss the procedures to disclose other pieces of information obtained from this investigation. Furthermore, having confirmed the presence of information networks for concerned parties in the U.S. and Japan, we have been investigating the feasibility of collaborating with these information networks. To contribute to the development of debris drift prediction method, we investigated the damage caused by the tsunami in connection with the land use of each disaster-stricken area in Tohoku and also conducted field surveys in Hokkaido coastal areas affected by the secondary disaster in order to obtain information on debris that drifted from the disaster areas. 3. Results and Discussion 3.1. Investigation of Drift Routes In this research, the three types of simulated debris with Argos transmitters were released three times until the end of FY2011. In FY2012, the debris location information from the transmitters was constantly gathered and the fourth release of simulated debris was conducted in January The general outline of the simulated debris used in a total of four release experiments is shown in Table 1-1 below: Table 1-1 Types of simulated debris released Type of simulated Subsurface type Standard type Floating type debris Sinking rate of Approximately 80% Approximately 50% Approximately 10% simulated debris (volumetric percentage beneath the sea surface) Image of floating simulated debris Actual objects envisioned Driftwood, lumber containing seawater, etc. Refrigerators, tires, containers, etc. Drifting ships and buoys Influences exposed to Strongly influenced Influenced both by Strongly influenced 2

7 by ocean current ocean current and westerlies Time of release January 2013 June 2011 October 2011 January 2012 January 2013 Points of release (the Off Miyako, Iwate The same as in the same for all 4 releases) Prefecture (Iwate) left column Off Kesennuma, Miyagi Prefecture (Miyagi) Off Soma, Fukushima Prefecture (Fukushima) by westerlies January 2013 The same as in the left column The results of the first to fourth releases are summarized as follows: From the results of the first and second releases, it was observed that the actual drift route differed considerably among different points of release even when the releases took place at the same time. However, by focusing on the results of the third and fourth releases, we also found that the simulated debris followed almost the same route for at least the first 1 to 3 months. On the basis of this finding, a prediction can be made that, even when a massive amount of drifting debris is produced, we can track the drift route for all debris for the initial 3 months by tracking only a portion of them. Furthermore, it has been found that secondary disaster caused by marine debris generated from the tsunami following the earthquake in Japan can occur not only overseas, such as in the West Coast of the U.S. to which attention tends to be focused, but also within Japan. For example, the simulated debris released off Miyako in the first release approached toward Hokkaido, following a route that would most likely lead to the debris reaching there. The simulated debris of the first and second releases off Soma drifted ashore in Miyagi and Ibaraki Prefecture (Ibaraki). As it has been confirmed that a secondary disaster caused by marine debris generated on March 11, 2011 can also occur in Japan, estimating its total volume and composition is a future task that should be addressed Investigation of Damage Situations and Generation Sources In this study, we conducted a field investigation in the Pacific coastal area of Hokkaido on the secondary disaster caused by marine debris generated from the tsunami following the earthquake on March 11, 2011 and collected basic data that can contribute to the development of measures to minimize the secondary disaster expected to be caused by driftage arriving at the west coasts of the U.S. This investigation has so far revealed that 50% to 97% of the disaster waste collected and disposed of in the Pacific coastal areas of Hokkaido consisted of driftwood from natural rivers 3

8 and that the percentages of artificial objects varied among regions. Considering that driftwood has always been characteristic debris in Hokkaido, a majority of artificial objects collected on the coasts are probably the ones generated in the disaster areas. When we look at the total amount of marine debris washed ashore in the Pacific coastal areas of Hokkaido, which is geographically close to the source of the marine debris generated and is susceptible to the secondary disaster caused by a large amount of marine debris arriving as influenced by ocean currents, we noted that the absolute amount of artificial objects is small. From this finding we consider that the expected secondary disaster caused by marine debris will not be as extensive as initially assumed. Furthermore, as the marine debris generated from the tsunami following the earthquake on March 11, 2011 was never observed during FY2012 after the debris was removed from the coasts by the end of FY2011, it is considered that secondary disaster in coasts should be of transient nature, and secondary disaster by marine debris is not likely to occur repeatedly Proposition of Multifaceted Use of Marine Debris Information In this research, information so far gathered regarding the marine debris generated from the tsunami following the earthquake on March 11, 2011 includes the following: (1) Actual data on the drift routes and information on the drift situation obtained from the simulated debris that were released at three points located off the Pacific Ocean side of Tohoku district and that had been prepared with the assumption of three types of driftage (i.e., subsurface type, standard type, and floating type) (2) Information on the volume, content, disposal method, cost, and criteria of driftage based on the field survey conducted at the sites in Japan where marine debris generated from the tsunami following the earthquake on March 11, 2011 arrived. As a result of our investigation on the drift route of simulated debris, it has been observed that the different types of simulated debris with transmitters that were released at different points eventually came closer together within a distance of a few hundred meters during their course of drifting and, then, began to scatter. Furthermore, a local resident reported to us that the simulated debris released off Miyako of Iwate on June 3, 2011 was found washed ashore on the coast of Arch Cape of Oregon, U.S, on March 18 (Mon) this year, after 1 year and 9 months. From the observation that the simulated debris released 3 months after the disaster to track its drift route has drifted ashore, it is presumed that marine debris generated from the tsunami following the earthquake on March 11, 2011 with a sinking rate similar to that of simulated debris should have already been washed ashore, although there are some uncertainties regarding its drift route and time as mentioned above. These results can be said to sustain part of the drift route prediction that has been announced by the Ministry of the Environment (MOE). The arrival of a large amount of debris has not yet been disclosed in detail, probably because (1) a large portion of driftage cannot be identified whether it is from the tsunami following the earthquake on March 11, 2011, (2) driftage is scattered and dispersed over a wide area of the 4

9 ocean, and (3) a large portion of driftage remains in the ocean, and the actual driftage on the coastal area does not necessarily have a large volume Discussion of Marine Debris Prediction Method On the basis of information materials such as reports already released, we have discussed a stochastic method based on the floor area affected and a stochastic method based on the number of houses affected. The number of houses damaged by the Great East Japan Earthquake has been announced by the Disaster Countermeasures Office of the Fire and Disaster Management Agency, which included the number of totally collapsed buildings, half collapsed buildings, partially damaged buildings, inundations above floor level, and inundations below floor level. Using the number of totally collapsed buildings and by using the above two methods, we estimated the volume of debris generated in three prefectures (Iwate, Miyagi, and Fukushima) owing to the Great East Japan Earthquake. The results were then compared with the estimated figures of debris generation prepared by the MOE for the purpose of verifying the validity of the above methods for estimating the volume of disaster-generated debris. 4. Contribution to Environment Policy Unlike the conventional technology to predict the drift route on the basis of computer simulation, in this study, we aimed to develop a drift route prediction method based on actual tracking using simulated debris with a transmitter and by releasing simulated debris ahead of the actual occurrence. As there has been no investigation of drift routes of marine debris based on collection of long-term actual data, the actual data obtained in this study should contribute to increasing the accuracy and evaluation of simulation. In addition, our approach is the first attempt in this field to organize information and knowledge about the damage caused by marine debris generated from the disaster and the sources of debris for systematic utilization of such information and knowledge. Furthermore, once specific details and the extent of a disaster secondary to a possible primary disaster are determined, necessary responses and practical countermeasures are prepared on the basis of these various types of information and knowledge obtained, which should be useful for the preparation of the Guidelines for prevention of secondary disaster caused by marine debris generated during tsunami events (Provisional) conducted by the national and local governments. 5. Feasibility of Results of Research The secondary disasters envisioned in this research cover those caused by marine debris generated from the tsunami after the earthquake on March 11, On the other hand, as a result of collecting information by field surveys and holding symposiums among others, it has become clear that the places likely to be affected by the marine debris have always been affected by marine debris that generally drifts ashore on a daily basis from various places within 5

10 and outside the country, causing various forms of damage. In this research, considering also the above situation, we aim to provide information, such as the properties, amount, and method of disposal specific for the marine debris generated from the tsunami after March 11, 2011, to concerned parties of the regions likely to be affected so that they can acquire specific knowledge about the details and situations associated with secondary disaster, which can be caused by driftage and drifted debris. From these results, we would like to propose the appropriate measures that should be taken for prevention of secondary disasters in the regions. 6. Conclusions As the result of this research, the following accomplishments were achieved: 1) From four releases of simulated debris with transmitters (a total of 18 transmitters) and tracking their drift routes, we were able to obtain actual data characteristic of the behavior of driftage, including data on the debris that was washed ashore on the West Coast of the U.S. 2) With the aim to clarify the damage caused by marine debris, we conducted a field survey and interview surveys in the affected area in Hokkaido and collected data on the type, properties, and disposal volume of coastal waste. 3) With the aim to prepare information to be provided to the regions likely to be affected by driftage, we have compiled drift route prediction results of marine debris generated from the tsunami on March 11, 2011 and identified probable secondary disasters caused by the driftage, thus clarifying the future tasks that should be addressed. 4) By compilation of the stochastic methods based on the floor area affected and the number of houses affected, we were able to verify a method to estimate the volume of the disaster debris and clarify the future tasks to be addressed. 7. Research Plan The following studies are scheduled for FY2013: 1) We plan to conduct a study utilizing the location information that has so far been obtained from the simulated debris to which transmitters were attached to improve the simulation models for drift route prediction of marine debris generated from the tsunami after the earthquake on March 11, 2011, and to compile a universal method for drift route prediction. Furthermore, we plan to collect actual data that can help predict the drift routes of marine debris generated from tsunami after the large earthquakes expected to occur in the near future in Kanto and Tokai districts. 2) As in FY2012, we plan to continue collecting information on secondary disasters caused by drifting debris and to propose measures to minimize possible secondary disasters by using the results of the drift route survey. 3) We plan to develop a method to determine the volume of marine debris generated by tsunami and to develop the recovery and disposal methods for sea drifting waste. 6

11 4) We plan to compile necessary information for the national and local governments to prepare the Guidelines for prevention of secondary disaster caused by marine debris generated during tsunami events (Provisional). 7

12 Chapter 2 Investigation of Drift Route 1. Research Objectives Information necessary for prediction of arrival date of marine debris and for effective debris recovery is referred to as the predictive information of drift route. According to the results of computer simulation performed by Dr. Maximenko of University of Hawaii in 2011, a massive amount of tsunami-generated debris was expected to reach Midway Islands during the winter of 2011 and spring of 2012, the main island of Hawaii in 2012 and 2013, and the west coast of North America in 2013 and 2014 [1]. However, as the data supporting this simulation are mostly taken using the buoys in the sea, the drifting pattern of these buoys may differ from that of actual drifting objects that are influenced by winds. On the other hand, in April 2012, the MOE of Japan released the simulation results obtained using different calculation methods for sinking rates of individual drifting objects [3]. In this simulation, a drifting object whose upper half was above the sea surface and the lower half beneath the sea surface was defined as the standard type and was predicted to reach the coastal region of the west coast of North America in or around October However, actually, the arrival of a massive amount of tsunami-generated waste in the North American continent was not observed at the predicted time. The MOE switched to a simulation method with higher reliability in November 2012 and announced the results of the second simulation; on the basis of the results, the arrival of a major portion of the standard-type marine debris was expected in December 2012 [4]. As of January 2013, however, it was not observed. Accordingly, as prediction by simulation can lead to different results depending on the original data and parameters, it is essential to verify the adequacy of original data and parameters. For this verification of adequacy, it is important to compare simulation data with actual debris location data. In this research, therefore, simulated debris equipped with a device that can transmit location information via satellite was actually released from points in the vicinity of the disaster-stricken area and location information was sent via satellite and accumulated. 2. Research Methodology The simulated debris was placed in a container with an Argos transmitter developed by Nomad Science Technology Inc. fitted inside. The Argos system can determine the transmitter location by analyzing the Doppler effect of electric waves sent from a transmitter to a dedicated satellite and can accumulate the information in the server. Users can access the server on the Internet to obtain the location information. Wherever in the ocean the transmitter was, its location information can be collected every time the satellite passed over the transmitter. The number of satellite transits was estimated to be a few times a day. Tottori University of Environmental Studies, the institution implementing this research, 8

13 released the simulated debris with an Argos transmitter three times by the end of FY2011 [2]. In FY2012, the location information from the transmitters was constantly collected and the fourth release of simulated debris was conducted in January The general outline of the simulated debris used in a total of four release experiments is shown in Table 2-1 below: Type of simulated debris Sinking rate of simulated debris (volumetric percentage beneath the sea surface) Image of floating simulated debris Table 2-1 Types of simulated debris released Subsurface type Standard type Float type Approximately 80% Approximately 50% Approximately 10% Actual envisioned objects Influences exposed to Driftwood, lumber containing seawater, etc. Strongly influenced by ocean current Refrigerators, tires, containers, etc. Influenced both by ocean current and westerlies Time of release January 2013 June 2011 October 2011 January 2012 January 2013 Points of release (the same for all 4 releases) Off Miyako, Iwate Off Kesennuma, Miyagi Off Soma, Fukushima The same as in the left column Drifting ships and buoys Strongly influenced by westerlies January 2013 The same as in the left column In this research, the percentage of the volume beneath the sea surface with respect to the total volume of the simulated debris was defined as the sinking rate. The simulated debris with a sinking rate of about 80% was defined as the subsurface type, that with a sinking rate of approximately 50% as the standard type, and that with a sinking rate of approximately 10% as the floating type. Until now and including FY2011, a total of four releases were conducted. Each time, simulated debris with the identical specifications was released from three different points, one for each point, in the disaster-stricken area. Thus, the differences in drift route among release points can be analyzed. With regard to the standard-type debris, the differences in drift route between individual times of release can also be analyzed by comparing the results taken from the debris released in June 9

14 2011, October 2011, and January Furthermore, by comparing the results taken from the debris released in January 2012 and January 2013, we can also analyze the differences in drift route between the years of release. In the fourth release conducted in January 2013, three different types of simulated debris were released from the same point at the same time. By comparing the results, we can also analyze the difference in drift route in terms of sinking rate. However, there is one thing that has to be kept in mind when we compare data taken from the standard-type simulated debris used in all four releases. During the course of this research, we searched for a method that can extend the battery life of transmitters. Therefore, the transmitter specifications are not the same among all four releases. Table 2-2 shows a summary of the specifications of transmitters used in the four releases: Table 2-2 Specifications of transmitters Release time Number of hours during which location information can be transmitted Sinking rate of subsurface type Sinking rate of standard type Sinking rate of float type Battery life 1st release experiment June 3 to June 19, hours in a day Approx. 35% Less than 6 months 2nd release experiment October 21 to 22, hours in a day Approx. 50% Less than 30 months 3rd release experiment January 29 to February 6, hours in a day Approx. 50% Less than 30 months 4th release experiment January 12 to 17, hours in a day Approx. 82% Approx. 50% Approx. 13% Less than 60 months The results of the three release experiments are detailed in the next section and after: 3. Results of the Second Release Experiment 3-1. Outline of the Second Release Experiment In the second release experiment in October 2011, three sets of the debris with transmitters (one for each release point) were released from almost the same points as in the first release. Table 2-3 shows the drift results obtained by January 10, 2013: Table 2-3 Trajectory of debris with transmitters in the second release (up to January 10, 2013) No. Trajectory Release point Release date Observed drift Yellow 50 km off October 22, After release, it moved in a circle within an 10

15 Miyako, Iwate Red 20 km off Kesennuma, Miyagi Blue 20 km off Soma, Fukushima 2011 area of about 200km and then meandered toward the southeast. As of Jan. 10, 2013, it is about 1,500 km from the release point. October 22, 2011 October 21, 2011 It drifted toward the east and, as of Jan. 10, 2013, it is at a distance of about 5,500 km from the release point. It drifted toward the south and, on November 2, 2011, was found washed ashore on the coast of Kamisu City, Ibaraki, at about 200km from the release point. For a comparison of differences among the three drift routes, Fig. 2-1 shows a map of the trajectories of the three sets of simulated debris. The drift route of the debris released in Iwate is shown in yellow, that released in Miyagi in red, and that released in Fukushima in blue. In 15 months, still drifting. In 2 weeks, it was found washed ashore. In 15 months, still drifting. Fig. 2-1 Location information of simulated debris in the second release (October 21, 2011 to January 10, 2013) As in the case of the first release experiment, three sets of the debris with transmitters clearly showed different drift routes. This time, however, the debris that continued to move in a circle for a while was that released from Iwate. The debris released from Iwate and Miyagi drifted southward almost to the same latitude and then suddenly started drifting eastward. The debris was probably first brought southward by the Oyashio Current and, after hitting the Kuroshio Current, started to drift eastward in the North Atlantic Current. The figure above shows that the debris released from Fukushima moved westward in a straight line after reaching Kamisu City of Ibaraki. This straight line shows the distance that the debris was mailed to Tottori after it was found on the coast by a resident, which, therefore, should not be taken as a part of its drift route Drift Route of Simulated Debris Released from Iwate 11

16 Next, the trajectory of each set of debris with transmitters is analyzed in detail. Figure 2-2 shows a map indicating the trajectory of the debris released from Iwate; the locations of the debris every 3 months from the day of release are indicated on the map. For a while after its release, it continued to move in a circle within an area of approximately 200 km from the release point and it finally left a vortex 2 months after its release. When and where it left the vortex is also indicated on the map. Then, it started to meander toward the southeast, and 15 months from the start, it was still drifting at a distance of 1,500 km south-southeast from the release point. Release point Left a vortex in 2 months In 12 months In 9 months In 3 months In 15 months, still drifting In 6 months Fig. 2-2 Location information of simulated debris released from Iwate in the second release 3-3. Drift Route of Simulated Debris Released from Miyagi Figure 2-3 shows a map indicating the trajectory of the debris with a transmitter released from Miyagi; the locations every other month from the day of release (October 22) are indicated on the map. While meandering, it reached the vicinity of the date line in about 4 months. Then, its speed decreased and the meandering pattern became more complicated. After 15 months, it was still drifting in the ocean due north of Hawaii. Release point In 6 months In 9 months In 3 months In 12 months In 15 months, still drifting Date line 12

17 Fig. 2-3 Location information of simulated debris released from Miyagi in the second release 3-4. Drift Route of Simulated Debris Released from Fukushima Figure 2-4 shows the location information of the debris with a transmitter released from Fukushima during a period from the day of release (October 21) to the day of arrival (November 2). The trajectory shows that it drifted southward from the release point along the Japanese islands until it was washed ashore in Kamisu City. Release point Found washed ashore after 2 weeks Fig. 2-4 Location information of simulated debris in the second release from Fukushima 4. Results of the Third Release Experiment 4-1. Outline of the Third Release Experiment In the third release experiment in January 2012, three sets of the debris with transmitters (one set for each release point) were also released from almost the same points as in the second release. Table 2-4 shows the drift results obtained by January 10, 2013: Table 2-4 Trajectory of debris with transmitters in the third release (up to January 10, 2013) No. Trajectory Release point Release date Observed drift Yellow 50 km off Miyako, Iwate Red 20 km off Kesennuma, Miyagi Blue 20 km off Soma, Fukushima February 6, 2012 January 29, 2012 January 31, 2012 It drifted toward the east and, as of Feb. 19, 2013, it was drifting at a distance of approximately 5,500 km from the release point. It drifted, meandering toward the east and, as of Feb. 19, 2013, it was drifting at a distance of approximately 4,000 km from the release point. It drifted toward the east and was drifting back and forth within an area of 1,000 3,000 km from the release point. As of Feb. 19, 2013, it was at a distance of approximately 2,700 km 13

18 from the release point. For a comparison of differences among the three drift routes, Fig. 2-5 shows a map of the trajectories of the three sets of simulated debris up to October For the first time, this research has identified that the simulated debris released from Fukushima has drifted toward the east. Fig. 2-5 Location information of simulated debris in the third release (January 29, 2012 to October 29, 2012) A unique result obtained was that the debris released from Miyagi and that released from Fukushima followed the same drift route for about 1,000 km and approached each other along the way within a few hundred meters Drift Route of Simulated Debris Released from Iwate Figure 2-6 shows a map indicating the trajectory of the debris released from Iwate; the locations of the debris every 3 months from the day of release are indicated on the map. While meandering, it reached the vicinity of the date line in approximately 5 months. Then, it slowed down and was drifting in the ocean due north of Hawaii as of 12 months after release. Release point In 12 months, still drifting In 3 months In 6 months In 9 months Date line 14

19 Fig. 2-6 Location information of simulated debris released from Iwate in the third release 4-3. Drift Route of Simulated Debris Released from Miyagi Figure 2-7 shows a map indicating the trajectory of the debris with a transmitter released from Miyagi; the locations every 3 months from the day of release are indicated on the map. After repeatedly meandering, it reached the vicinity of the date line in about 9 months. Release point In 6 months In 9 months In 12 months, still drifting In 3 months Date line Fig. 2-7 Location information of simulated debris released from Miyagi in the third release 4-4. Drift Route of Simulated Debris Released from Fukushima Figure 2-8 shows a map indicating the trajectory of the debris with a transmitter released from Fukushima; the locations of the debris every 3 months from the day of release are indicated on the map. After heading toward the east, it was drifting back and forth within an area of 1,000 3,000 km from the release point. In 9 months In 3 months In 6 months Release point In 12 months, still drifting Fig. 2-8 Location information of simulated debris released from Fukushima in the third release 15

20 5. Results of the Fourth Release Experiment 5-1. Outline of the fourth Release Experiment The fourth release experiment was conducted in January, In this experiment, three different types of simulated debris were released from the same points. The objective of this investigation was to analyze the difference in drift route in terms of sinking rate. Table 2-5 shows the floating states of released simulated debris. Table 2-5 Floating states of released simulated debris Type of simulated Subsurface type Standard type Floating type debris Sinking rate Approx. 82% Approx. 50% Approx. 13% Shape Disk shape and PET bottle shape Barrel shape cylindrical shape Total volume Approx Approx Approx Floating state 5-2. Drift Routes of Subsurface-Type Simulated Debris Table 2-6 shows the drift routes (up to February 19, 2013) of the subsurface-type simulated debris released from three different points. Table 2-6 Drift routes of subsurface-type simulated debris in the fourth release No. Trajectory Release point Release date Observed drift Yellow 50 km off Miyako, Iwate Red 20 km off Kesennuma, Miyagi Blue 20 km off Soma, Fukushima January 12, 2013 January 12, 2013 January 17, 2013 It drifted toward the southeast, and as of Feb. 19, 2013, it was at a distance of approximately 1,600 km from the release point. It drifted toward the southeast, and as of Feb. 19, 2013, it was at a distance of approximately 1,600 km from the release point. It drifted toward the southeast, and as of Feb. 19, 2013, it was at a distance of approximately 600 km from the release point. Figure 2-9 shows a map of the trajectories of the subsurface-type simulated debris up to February 19, The simulated debris released from Iwate and Miyagi followed similar meandering routes. Although having slowed down, the debris released from Fukushima also followed a route similar to the debris released from Iwate and Miyagi. 16

21 Release point: off Miyagi Release point: off Iwate Release point: off Fukushima 1 month after released from Miyagi 1 month after released from Fukushima 1 month after released from Iwate Fig. 2-9 Location information of subsurface-type simulated debris in the fourth release (January 12 to February 19, 2013) 5-3. Drift Routes of Standard-Type Simulated Debris Next, the drift routes of the standard-type simulated debris up to February 19, 2013 are shown in Table 2-7. Table 2-7 Drift routes of standard-type simulated debris in the fourth release No. Trajectory Release point Release date Observed drift Yellow 50 km off Miyako, Iwate Red 20 km off Kesennuma, Miyagi Blue 20 km off Soma, Fukushima January 12, 2013 January 12, 2013 January 17, 2013 It drifted while meandering toward the south, and as of Feb. 19, 2013, it was at a distance of approximately 400 km from the release point. It drifted toward the southeast, and as of Feb. 19, 2013, it was at a distance of approximately 2,000 km from the release point. It drifted toward the southeast, and as of Feb. 19, 2013, it was at a distance of approximately 1,000 km from the release point. Figure 2-10 shows a map of the drift routes of three sets of standard-type simulated debris up to February 19, The simulated debris released from Miyagi was drifting toward the east-southeast. The simulated debris released from Fukushima showed a meandering path that was different from that released from Miyagi and its drift was slower. However, its path did not deviate largely from the path of that released from Miyagi. Only the one released from Iwate slowed down on the ocean at a distance up to about 400 km from the release point and was meandering. However, this, too, did not deviate largely from the path of Miyagi s. 17

22 Release point: off Miyagi Release point: off Fukushima Release point: off Iwate 1 month after released from Iwate 1 month after released from Miyagi 1 month after released from Fukushima Fig Location information of standard-type simulated debris in the fourth release (January 12 to February 19, 2013) 5-4. Drift Routes of Floating-Type Simulated Debris Next, the drift routes of the floating-type simulated debris up to February 19, 2013 are shown in Table 2-8. Table 2-8 Drift routes of floating-type simulated debris in the fourth release No. Trajectory Release point Release date Observed drift Yellow 50 km off Miyako, Iwate Red 20 km off Kesennuma, Miyagi Blue 20 km off Soma, Fukushima January 12, 2013 January 12, 2013 January 17, 2013 It drifted toward the southeast and, as of Feb. 19, 2013, it was at a distance of approximately 1,500 km from the release point. It drifted toward the southeast and, as of Feb. 19, 2013, was at a distance of about 1,500 km from the release point. It drifted toward the southeast and, as of Feb. 19, 2013, was at a distance of about 1,500 km from the release point. Fig shows the drift routes of three sets of floating-type simulated debris. All of them have been following almost the same paths. Release point: off Miyagi Release point: off Iwate Release point: off Fukushima 1 month after released from Iwate 1 month after released from Fukushima 1 month after released from Miyagi 18

23 Fig Location information of floating-type simulated debris in the fourth release (January 12 to February 19, 2013) 5-5. Comparison among Three Types of Simulated Debris Released from Iwate In the sections from 5-2 to 5-4, a total of nine sets of simulated debris in the fourth release experiment were compared to determine how the drift route of the same type of simulated debris could differ depending on the release point, for which data were sorted by type of the simulated debris. Furthermore, in this section and hereafter, the three different types of simulated debris released from the same point are compared to determine how they can differ in drift route. First, the correspondence between the numbers and the new colors for the three types of simulated debris that were released off Iwate is shown in Table 2-9 below: Table 2-9 Colors for Simulated Debris from Iwate in the Fourth Release No. Trajectory Type of simulated debris Observed drift Yellow Floating type See Table Purple Standard type See Table Green Subsurface type See Table 2-6. Figure 2-12 shows the drift routes indicated by new colors. Although the floating type and the subsurface type followed different meandering routes, both showed almost the same direction and speed, and showed overlapping in locations in 1 month. Only the standard type continued to meander after its drift speed decreased in the ocean at a distance of about 400 km from the release point. However, for this type also, its path did not deviate largely from those of the floating type and the subsurface type. Release point: off Iwate Standard type: in 1 month Floating type: in 1 month Subsurface type: in 1 month Fig Simulated debris released from Iwate in the fourth release (January 12 to February 19, 2013) 5-6. Comparison among Three Types of Simulated Debris Released from Miyagi 19

24 The correspondence between the numbers and the new colors for the three types of simulated debris that were released off Miyagi is shown in the Table 2-10 below and the drift route data indicated in new colors are shown in Fig All of the three types followed almost the same routes up to a distance of 700 km from the release point off Miyagi. Then, only the route of the floating type largely deviated from the routes of the other types, whereas the standard type and the subsurface type remained close in their routes. Table 2-10 Colors for Simulated Debris from Miyagi in the Fourth Release No. Trajectory Type of simulated debris Observed drift Yellow Floating type See Table Purple Standard type See Table Green Subsurface type See Table 2-6. Release point: off Miyagi Subsurface type: in 1 month Standard type: in 1 month Floating type: in 1 month Fig Simulated debris released from Miyagi in the fourth release (January 12 to February 19, 2013) 5-7. Comparison among Three Types of Simulated Debris Released from Fukushima The correspondence between the numbers and the new colors for the three types of simulated debris that were released off Fukushima is shown in Table 2-11 below and the drift route data indicated in new colors are shown in Fig Table 2-11 Colors for Simulated Debris from Fukushima in the Fourth Release No. Trajectory Type of simulated debris Observed drift Yellow Floating type See Table Purple Standard type See Table Green Subsurface type See Table

25 Release point: off Fukushima Subsurface type: in 1 month Standard type: in 1 month Floating type: in 1 month Fig Simulated debris released from Fukushima in the fourth release (January 12 to February 19, 2013) As in the case of the different types of simulated debris that were released from Iwate and Miyagi, those that were released from Fukushima also followed almost the same routes while meandering, although each type varied in speed. 6. Summary From the results of the second release, it was observed that the drift routes could vary greatly depending on release point even when the releases took place at the same time. However, a more detailed study of the results of the third and fourth releases in January showed that the simulated debris followed almost the same route for at least 1 to 3 months. On the basis of this finding, a prediction can be made that, even when a massive amount of drifting debris is produced, we can track the drift route of the entire debris for the initial 3 months by tracking only a portion of them. Furthermore, it has been found that the secondary disaster caused by marine debris generated from the tsunami following the earthquake in Japan can occur not only overseas such as in the West Coast of the U.S. to which attention tends to be focused, but also within Japan. For example, the simulated debris released off Iwate in the first release in June 2011 was found approaching toward Hokkaido, following a route that would most likely take the debris there. The simulated debris in the first and second releases off Fukushima has drifted ashore in Miyagi and Ibaraki. As it has been confirmed that secondary disaster caused by debris generated by the tsunami on March 11, 2011 can also occur in Japan, estimating the total volume and composition of debris should be a future task to be addressed. It has also been confirmed from the first release that a portion of debris was caught in a small current eddy and remained in the Japanese coastal waters for a long time. Although this small current eddy may eventually collapse or move, the marine debris generated from the tsunami on March 11, 2011 may temporarily accumulate in it. Because of the small number of sets of simulated debris that were released in this research, it 21

26 is difficult for us to draw any common conclusion by regarding them as if they were typical values. However, by comparison and analysis of differences in release time, release point, and sinking rate, we expect to obtain an effective feedback on the simulation model. On the other hand, we have received the report that the simulated debris released in June 2011 was found washed ashore on a coast of Arch Cape of Oregon, U.S, on March 18 (Mon), 2013, 1 year and 9 months after its release. As this simulated debris had a battery whose lifetime was within 6 months, transmission was lost in the Pacific Ocean. Although not all the routes in between could be clearly tracked, the validity of this research method with the aim to identify actual movements or routes was demonstrated. It has not yet been determined whether this particular simulated debris was released from a point 20 km off the coast of Miyako, Iwate or from a point 20 km off the coast of Kesennuma, Miyagi. However, we expect to identify its release point upon the recovery of this simulated debris. In addition, although we know that the simulated debris is of the standard type with a sinking rate of 35%, we would also like to clarify following its recovery and analysis whether its shape and sinking rate were retained until the time it drifted ashore. (References) [1] Nikolai Maximenko, Modeling the motion of marine debris historical trajectories of drifting buoyst [Presentation in the International Symposium of Tottori University of Environmental Studies: Tracking and Countermeasure of marine debris after the Great East Japan Earthquake (2011) [2] Masaru Tanaka, Makoto Okazaki, Tomomichi Kobayashi, Haruo Matsumura, Tetsuji Arata, Shin Sato, Koki Nishizawa, Yasuhiko Kagami, Study on reduction of marine debris generation and promotion of its recovery and disposal on the Sea of Japan coast, report of FY2011 research project subsidized by the Environment Research and Technology Development Fund (2012) (In Japanese) [3] Office of Marine Environment, Water Environment Division of Environmental Management Bureau, the Ministry of the Environment: Publication of results of drift route prediction of marine debris generated from the Great East Japan Earthquake (2012) (In Japanese) [4] Office of Marine Environment, Water Environment Division of Environmental Management Bureau, the Ministry of the Environment: Publication of intermediate results of drift route prediction of marine debris generated from the Great East Japan Earthquake (2012) (In Japanese) 22

27 Chapter 3 Investigation of Damage Caused by Marine Debris and Source of Debris Generation 1. Introduction As part of the factual survey on secondary disaster caused by marine debris generated from the tsunami following the Great East Japan Earthquake, we conducted a field survey and an interview survey with the personnel in charge of the management of the disaster-generated marine debris in Hokkaido, with the aim to obtain basic information that may contribute to studies on how to minimize possible secondary disaster that may be caused by marine/drifted debris from the tsunami after the Great East Japan Earthquake. The details of the surveys are reported in this chapter. 2. Interview Survey to Gather Data on Actual Secondary Disaster in Entire Hokkaido Caused by Marine Debris from the March 11, 2011 Tsunami An interview survey was conducted with the personnel of the Recycling Society Promotion Division, Bureau of Environmental Affairs, Department of Environment and Lifestyle, Hokkaido Government. The following results were obtained: 2-1. Study Areas Covered in Waste Weight Estimation The areas covered included the Pacific Ocean coastal zone from Shikabe Town to Hamanaka Town, which are the actual disaster-affected areas Weight of Waste from Disaster on March 11, 2011 The estimated weight of waste from the disaster on March 11, 2011 excluding tsunami sediment was 8,922 tons. This included waste derived from the primary tsunami-generated disaster and waste from the secondary disaster caused by drifted debris, which could not be separated from each other. Of this total weight, 81% or 7,243 tons has already been disposed. A majority of the disaster-generated waste has been disposed in landfills as general wastes, whereas as much as 40% has been recycled. Table 3-1 shows the estimated weights of disaster-generated waste in municipalities that have conducted disaster-generated waste management and the progress of waste management as of July

28 The regions where disaster-generated waste disposal has been carried out in Hokkaido are indicated by a red line. Table 3-1 Estimated weights of disaster-generated waste in municipalities in Hokkaido and the progress of waste management. Name of municipality Estimated weight of disaster-generated waste (ton) Waste disposal progress rate (%) Shikabe Town Mori Town Oshamambe Town Hakodate City Yakumo Town 3, Hiroo Town Toyokoro Town Muroran City Date City Toyoura Town Toyako Town Mukawa Town Biratori Town Hidaka Town Urakawa Town Samani Town Erimo Town Shinhidaka Town Akkeshi Town Hamanaka Town

29 As shown in Table 3-1, the estimated weight of disaster-generated waste in Yakumo Town is large. This is because of the direct damage to its scallop culture facilities caused by the tsunami. Fishery-related waste generated in the sea has accumulated at the sea bottom and has been taking much time to lift, hampering the progress in waste removal. On the other hand, as Table 3-1 does not include the data for Kushiro City, Onbetsu Town, Shiranuka Town and Kushiro Town, which are under the jurisdiction of the Kushiro General Subprefectural Bureau, Hokkaido Government, we needed to gather data also for the Kushiro district in order to clarify the drift of disaster-generated waste in the entire area along the Pacific Ocean. Therefore, we successively conducted an interview survey with the Kushiro General Subprefectural Bureau. 3. Interview Survey with the Kushiro General Subprefectural Bureau 3-1. Research Objectives As the objectives of this research, we conducted an interview survey in order to obtain information such as that on the occurrence of direct secondary disaster and measures carried out by the Kushiro General Subprefectural Bureau in response to such a disaster in places where marine debris generated from the tsunami following the Great East Japan Earthquake had actually arrived. Moreover, we also obtained quantitative information, for example, that on debris composition, disposal method, and cost of disposal of marine/drifted debris from the March 11, 2011 tsunami Research Methodology The Kushiro General Subprefectural Bureau has already prepared quantitative data regarding marine/drifted debris generated from the tsunami following the Great East Japan Earthquake that were collected and disposed in Kushiro City, Shiranuka Town, Kushiro Town, Akkeshi Town, and Hamanaka Town, which are located along the coast within its jurisdiction. For the purpose of this research and by face-to-face interview, we (1) investigated the following items and (2) requested for quantitative data such as the weight of disposed debris. 25

30 Factual survey on direct secondary disaster Actual state of occurrence of direct secondary disaster Place of occurrence of direct secondary disaster (geological formation and details) Types and weights of debris that caused direct secondary disaster Countermeasures against direct secondary disaster Factual survey on management of disaster-generated waste Weight of disaster-generated waste collected and transported Disposal method and implementing body of collection/disposal by waste type Weight and percentage of each waste type (composition) disposed Disposal method, disposal cost, financing body (project name) and time of disposal To clarify the occurrence of direct and broad secondary disaster and to discuss methods to minimize possible secondary disaster Estimation of composition percentage of marine/drifted debris generated from the disaster Fig. 3-1 Outline of this research 3-3. Investigated Items (Questions and Answers) The questions and answers given in the face-to-face interview survey are as follows: (1) Items regarding direct secondary disaster Item Questions Answers 1 Time of occurrence, place (geological formation), and details of direct secondary disaster No direct secondary disaster has been reported. 2 Types and weights of debris that caused direct (No answer) secondary disaster 3 Countermeasures against direct secondary disaster (No answer) * The direct secondary disaster includes specific secondary disaster such as human damage, physical damage, fishery damage, and loss of tourism resources, and does not include the broad secondary disaster such as damage to scenery and human labor/financial burden in waste collection, transport, and disposal. (2) Items regarding disposal of disaster-generated waste Item Questions Answers 1 Please give us data on actually disposed disaster-generated waste (weights of collected/ We can supply electronic numerical data. transported/disposed waste) in the municipalities within your jurisdiction. 2 Please give us, if possible, information on the cost, financing body (project name) and time of actual disposal of waste. We will discuss if it is possible to disclose information on disposal cost. 3 Please give us information on the disposal They were mainly implemented by method by waste type and the implementing the private sector to which works 26

31 body of collection/disposal. 4 Please give us information on the amount and percentage by type (composition) of wastes that have been disposed. 5 As for the wastes mentioned in items 2 to 4, do they only include waste generated from the tsunami following the Great East Japan Earthquake? Furthermore, are the debris generated locally, for example, from collapsed/damaged structures, separated from marine/drifted debris generated in other areas? were entrusted. We can supply electronic numerical data. The percentage of driftwood is predominantly high, all of which could not have been generated from the tsunami following the Great East Japan Earthquake. Locally generated debris cannot be separated from the marine/drifted debris generated in other areas Summary of Data on Marine/Drifted Disaster-generated Debris, etc. On the basis of the face-to-face interview survey, we have tallied and analyzed the numerical data, such as the weight of disposed marine/drifted disaster-generated debris, that we obtained from the Kushiro General Subprefectural Bureau and summarized them as follows. In this regard, all the expenses required for collection, transportation, and disposal were paid by the Green New Deal Fund. (1) Weights of coastal waste disposed by municipalities Coastal wastes that were collected, transported, and disposed during FY2011 were then summarized by municipality, together with the total shoreline length covered and the amount of drifted debris per unit length. Table 3-2 shows the relationships between the type and the disposal method of coastal waste. Because driftwood was the predominant (whose types and their percentages will be described in detail later), chipping accounts for more than 90% of all the disposal methods. As for individual municipalities, as shown in Table 3-3, the amount of disposed coastal waste was markedly high in Onbetsu Town. In combination with that in Shiranuka Town, the amount accounted for almost 90% of the total amount. Table 3-2 Types of coastal waste and disposal methods Type of coastal waste Disposal method Lumber Chipping Driftwood Fishery plastics (buoy, etc.) Landfilling Ropes, fishing nets, etc. 27

32 Other plastics (PET bottles) Metal trash Scrap tires Home electric appliances Recycling Municipality Fiscal year of implement ation Table 3-3 Amount of disposed coastal waste by municipality Amount of disposed waste (t) Incinera tion (t) Chippin g (t) Green New Deal Fund project Recycle Landfill Untre (t) (t) ated (t) Other s (t) Total (t) Total shorelin e length (m) Amount of drifted debris per unit length (kg/m) Kushiro , City Onbetsu , Town Shiranuka , Town Kushiro , Town Akkeshi , Town Hamanaka , Town River , zone Total , , , , (2) Percentage by type of coastal waste Table 3-4 and Fig. 3-2 show the percentage by type of coastal wastes that were collected, transported, and disposed. Driftwood accounted for 93% of the coastal waste in the whole area within the jurisdiction and the percentage of driftwood reached 98% in the river zone. From this, it can be presumed that the majority of driftwood must have most likely originated inland and drifted via rivers and then washed ashore. Table 3-4 Percentage by type of coastal waste Dispo sal Metho d Lumb er Drift wood Fisher y plastic s (buoy, etc.) Ropes, fishin g nets, etc. Other plastic s Home electri c applia Kushiro City Onbetsu Town (Kushiro City) Amo Percen Amo Percen unt tage unt tage of by of by dispo type dispo type sed (%) sed (%) wast wast e (t) e (t) Shiranuka Town Kushiro Town Akkeshi Town Hamanaka Town Amo Percen Amo Percen Amo Percen Amo Percen unt tage unt tage unt tage unt tage of by of by of by of by dispo type dispo type dispo type dispo type sed (%) sed (%) sed (%) sed (%) wast wast wast wast e (t) e (t) e (t) e (t) River zone Amo unt of dispo sed wast e (t) Percen tage by type (%) Total Amo unt of dispo sed wast e (t) , Percen tage by type (%)

33 nces Metal trash Scrap tires Subtot al excl. driftw ood Total , As for the percentage by type excluding driftwood, ropes, fishing nets and the like showed the highest at 37.4% for the whole area within the jurisdiction, followed by home electric appliances (e.g., refrigerator) at 27.9% and lumber at 17.0%. Although it was difficult to identify whether these items were generated from the March 11, 2011 tsunami, we assumed them as those generated from the tsunami and we took these percentages as the basis for our discussion on how to minimize possible secondary disaster in the future. 29

34 Driftwood 75.9% Driftwood 98.5% Driftwood 70.5% Driftwood 59.7% Home electric appliances (e.g., refrigerator) Other 26.7% plastics 2.0% Ropes, fishery nets, etc. 29.1% Ropes, fishery nets, etc. 39.4% Fishery plastics (e.g., buoy) 1.5% Metal trash 15.2% Metal trash 29.4% Scrap tire 0.9% Lumber 10.5% Percentage by type of coastal drifted waste (Kushiro City) Scrap tire 15.2% Lumber 6.1% Fishery plastics (e.g., buoy) 24.2% Percentage by type of coastal drifted waste in the river zone Fishery plastics (e.g., buoy) 1.8% Ropes, fishery nets, etc. 21.3% Lumber 38.2% Home electric appliances (e.g., refrigerator) 37.6% Metal trash 1.0% Percentage by type of coastal drifted waste (Kushiro Town) Fishery plastics (e.g., buoy) 2.6% Ropes, fishery nets, etc. 26.9% Lumber 32.6% Other plastics 1.8% Home electric appliances (e.g., refrigerator) 26.8% Metal trash 5.4% Scrap tire 3.8% Percentage by type of coastal drifted waste (Hamanaka Town) Driftwood 97.4% Driftwood 91.7% Other plastics 1.2% Ropes, fishery nets, etc. 63.4% Ropes, fishery nets, etc. 33.6% Other plastics 4.4% Percentage by type of coastal drifted waste (Onbetsu Town) Home electric appliances (e.g., refrigerator) 41.4% Home electric appliances (e.g., refrigerator) 4.1% Metal trash 12.0% Scrap tire 1.0% Lumber 12.6% Fishery plastics (e.g., buoy) 2.5% Metal trash 4.1% Scrap tire 3.6% Lumber 10.8% Fishery plastics (e.g., buoy) 5.5% Percentage by type of coastal drifted waste (Shiranuka Town) Driftwood 72.2% Driftwood 93.0% Other plastics 2.1% Ropes, fishery nets, etc. 32.1% Fishery plastics (e.g., buoy) 0.7% Ropes, fishery nets, etc. 37.4% Other plastics 2.4% Home electric appliances (e.g., refrigerator) 29.1% Lumber 26.9% Percentage by type of coastal drifted waste (Akkeshi Town) Metal trash 5.0% Scrap tire 3.8% Home electric appliances (e.g., refrigerator) 27.9% Metal trash 9.8% Lumber 17.0% Fishery plastics (e.g., buoy) 3.3% Percentage by type of coastal drifted waste (within jurisdiction of Kushiro General Subprefectural Bureau) Scrap tire 2.5% Fig 3-2 Percentage of coastal waste by type and municipality 30

35 4. Consideration on Secondary Disaster Expected to Occur Based on Field Survey of Drifted Debris in Hokkaido It has been clarified that, among the disposed disaster-generated wastes in the Pacific coastal regions of Hokkaido where we conducted our research during this fiscal year, driftwood from natural rivers accounted for 50% to 97%, whereas the percentages of man-made drifted debris varied considerably among regions (Table 3-4). As driftwood has always been characteristic drifted debris of Hokkaido, it can be presumed that the majority of man-made type of drifted debris must have been generated in the disaster-stricken areas. In the Pacific coastal areas of Hokkaido, which is geographically close to the source of disaster-generated drifted debris and is most likely susceptible to the secondary disaster caused by a large amount of marine debris arriving as influenced by ocean currents, the percentage of man-made debris with respect to driftwood was small and all of the waste has already been treated. This shows that the secondary disaster was less severe than what had been predicted. In addition, it was found by the interview survey that no new arrival of disaster-generated drifted debris was observed in this fiscal year after debris removal in the previous fiscal year. From these findings, we presume that the secondary disaster occurring on the coast must most likely be transient in nature and that the possibility of repeated recurrences is low. As for marine debris that are expected to reach the West Coast of the U.S., from the University s tracking survey of the simulated debris we have released, most of the marine debris is presumed to be drifting in the ocean in a dispersed manner and it is extremely difficult to predict the size and location of arriving debris and the specific details of possible secondary disaster. Considering the composition of marine debris observed in Hokkaido, the risk of severe water pollution or marine life damage is not expected to be high for the areas with arrival of marine debris. However, it is necessary to respond in an expeditious way to marine debris recovery work of other countries by disclosing information on the composition of marine debris in Hokkaido and by showing countermeasures for collection, and disposal. Besides secondary disaster caused by coastal debris washed ashore, the actual situations of secondary disaster caused by debris accumulated on the sea bottom are unknown, because as yet, there has been no method developed to investigate the amount and composition of such debris. In order to prevent secondary disaster in fishery and to contribute to the speedy recovery of the disaster-stricken areas, it is necessary for us to discuss a method to investigate debris accumulated on the sea bottom and to develop measures to grasp the actual situations. 5. Summary Through a factual survey on secondary disaster caused by disaster-generated marine debris in 31

36 Hokkaido, we were able to obtain information on the type and amount of drifted debris, time of debris arrival, and response measures in terms of collection and disposal. Although the actual situations of secondary disaster caused by the disaster-generated wastes accumulated on the sea bottom and the research methodology for such wastes are left for a future study, the results of this research are expected to well contribute to minimizing secondary disaster caused by the disaster-generated marine debris that can reach other countries. 32

37 Chapter 4 Proposal of Multifaceted Utilization of Marine Debris Information 1. Utilization of Marine Debris Information Marine debris generated from the tsunami triggered by the Great East Japan Earthquake not only blocked the harbors where the tsunami occurred, damaged the fishing ground environment, and caused problems in ship navigation but also posed similar problems to other places where it drifted ashore and adversely affected the tourist industry and fishery of the coastal areas. In this chapter, we discuss these secondary disasters caused by the marine debris as against the disasters directly caused by the tsunami. As was shown in Chapters 2 and 3, the information on the marine debris from the March 11, 2011 tsunami that has so far been obtained in this research includes the following: (1) Actual data on the drift routes of simulated debris (three types, namely, subsurface type, standard type, and floating type) released from three points off the Pacific coast of Tohoku District and the information on drifting state obtained from the data, and (2) Information, such as the amount of marine debris, its details, disposal method, disposal cost, and evaluation criteria of drifted debris, based on the results of field surveys of sites in Japan where marine debris generated from the March 11, 2011 tsunami arrived. In this chapter, by referring to the outcomes of the domestic symposium on how to detect and manage drifted debris that was held in July 2012 in the university as well as the international symposium on international efforts to address damage caused by marine debris that was held in December of the same year, we summarize below how to utilize these pieces of information as well as the detailed content, how to acquire, and how to distribute the information that are needed for future studies. 2. Necessity of Provision of Information on Marine Debris and Drifted Debris from the March 11, 2011 Tsunami In early August 2012, a U.S.-Japan NGO meeting was held in Portland in Oregon, U.S.A, led mainly by the Ocean Conservancy (OC) on the U.S. side and General Incorporated Association JEAN on the Japanese side, both of which have been collaborating in the International Cleanup Campaign (ICC) activity. In the meeting, opinions on the disaster-generated marine/drifted debris were actively exchanged. Opinions and matters of concern expressed by the U.S. side were as follows [1]: 1) They would like to know when, what kind, and how much debris will arrive in their region. They worry because these things are unknown until debris actually arrives. 2) As their cleanup activity covers a large area, necessary equipment, including a ship and a light aircraft to visit the coasts, is costly. The number of volunteers can increase if they are provided funds for gasoline, for example. 3) Fishery-related equipment made of polystyrene foam may disintegrate into fine particles, 33

38 which may scatter in the environment during wintertime when their cleanup activity cannot be conducted; these fine particles may be accidentally digested by wild marine animals. 4) There are widespread worries about the possible spread of radioactive materials through the disaster-generated marine/drifted debris. Efforts should be made to disseminate the facts that the nuclear accident happened after the outflow of debris generated from the tsunami and that no radioactive materials are detected by inspection. 5) High disposal cost is required if many pieces of large marine debris that needs to be demolished drift ashore. 6) As the budget allocated by the state and federal governments for addressing marine debris is very limited, they would like to appeal for a greater budgetary provision. 7) Sharing information is important. Therefore, opportunities such as this meeting should be continuously provided. 8) As for the possibility of arrival of any mementos for disaster victims, if objects whose owners can be identified are found, efforts are to be made to retrieve such objects and deliver them to their owners. 9) Dispatching volunteers or concerned individuals from Japan to collect marine debris is not cost-effective, as adjusting the time of travel preparation and related activities is difficult because the arrival time and amount of marine debris are not known beforehand. In addition, the time to retrieve marine debris at the site is substantially limited in terms of travelling time and expenses. 10) It is important to discuss countermeasures against massive outflow of debris generated from the tsunami not only simply from the viewpoint of disaster-derived waste but also in connection with long-existing issues on marine debris. 11) As the west coast of the U.S. and Hawaii are the places where marine debris from Japan and Asian countries have often been drifted ashore, it is difficult to identify whether or not they are disaster-derived. It has been found important that a system be established to provide necessary information in response to these opinions and outstanding matters of concern. 3. Results of Drift Route Prediction of Marine Debris from the March 11, 2011 Tsunami Marine debris generated from the tsunami on March 11, 2011 is now drifting in the Pacific Ocean and is predicted by concerned institutions to be washed ashore in the Pacific islands and the west coasts of the U.S. and Canada. In particular, the drift route prediction [2] reported by the Ministry of Environment in April 2012 included a simulation in which the drift speed of marine debris was calculated from the speed of debris drifted by ocean currents and the speed of debris drifted by wind flow (leeway), which were combined on the assumption that no debris 34

39 sank to the bottom nor was collected. As the impact of current and leeway varies depending on the shape of marine debris, the simulation was implemented by dividing marine debris into three different types, i.e., 1) standard type whose upper half is above the sea surface and lower half is beneath the sea surface, 2) floating type whose part above the sea surface is about twice as large as the part beneath the sea surface, and 3) subsurface type whose most part is beneath the sea surface. The images taken by the Advanced Land Observing Satellite (ALOS) Daichi of Japan Aerospace Exploration Agency (JAXA) were used for setting the initial conditions. According to this report, the prediction until June 2013 has been reported as follows: 1) Standard type (volume above sea surface : volume beneath sea surface = 1 : 1): predicted to drift eastward in the Pacific Ocean and, after passing north of Hawaii, to reach the coastal areas of the west coast of the North American Continent around October ) Floating type (volume above sea surface : volume beneath sea surface = 2 : 1) : predicted to drift eastward in the Pacific Ocean and pass north of Hawaii. Part of this type will then come close to the west coast of Canada around February 2012 and reach the west coast of the North American Continent around October ) Subsurface type (volume above sea surface : volume beneath sea surface = 0 : 1) : predicted to drift eastward in the Pacific Ocean and, after passing north of Hawaii, to reach the waters off the west coast of the North American Continent around June Considering the strong influence of along-shore current, the predicted risk is low for this type being actually washed ashore on the coast. In the intermediate results of drift route prediction [3] reported in November 2012, analysis was carried out using actual data taken until June 2012 and by reproducing more realistic movements in the oceanic and atmospheric fields on the basis of wind data at shorter intervals. As for the floating type, the type of debris whose part above the sea surface is far bigger than the part beneath the sea surface (volume above sea surface : volume beneath sea surface = 4 : 1) was newly included in the assumption. According to this report, the prediction until June 2013 has been reported as follows: 1) Subsurface type (volume above sea surface: volume beneath sea surface = 0 : 1): predicted to drift eastward in the Pacific Ocean and, after passing north of Hawaii, to start to approach the coastal areas of the west coast of the North American Continent around June ) Standard type (volume above sea surface: volume beneath sea surface = 1 : 1): predicted to start to reach the coastal areas of the west coast of the North American Continent around December 2012, after remaining between Hawaii and the North American Continent from August to October ) Floating type [I] (volume above sea surface : volume beneath sea surface = 2 : 1): Most of this type is expected to have already reached the coastal areas of the west coast of the North American Continent as of August Part of this type drifting in the Pacific Ocean is 35

40 predicted to travel toward the west and start to reach the Philippine Sea by February ) Floating type [II] (volume above sea surface : volume beneath sea surface = 4 : 1) : Most of this type is expected to have already reached the coastal areas between Canada and Alaska as of August Part of this type drifting in the Pacific Ocean is predicted to travel toward the west and then to gradually disperse. With regard to the actual situation of marine debris from the March 11, 2011 tsunami washed ashore overseas, it has been reported that the Gyoun Maru No.11 that had been moored at Hachinohe Port was found drifting as an unmanned ship in the sea off the west coast of Canada and off Alaska (sunk when shot by the United States Coast Guard (USCG)). In addition, it was also reported that mementos, such as a volleyball and a soccer ball, and a container carrying motorbikes were washed ashore. These objects correspond to the floating type of marine debris in the results of drift route prediction reported by the MOE. What is noteworthy is about the four floating piers swept away from the Misawa Fishing Port by the tsunami on March 11, The first of them was found washed ashore on the coast of New Port, Oregon on June 5, 2012, while the second was detected drifting 15 miles off the Molokai of Hawaii on September 22, 2012 and the third was found washed ashore on the coast of Olympic Peninsula of Washington on December 18, This indicates the difficulty in predicting the drift route as even the objects swept away from the same spot can be dispersed following different routes, and washed ashore at very different places and very different times. As a result of the university s research on drift route using simulated debris, it was found that the different sets of simulated debris (to each of which a transmitter was attached) that were released from different places came close each other on the way within a few hundred meters and were then separated by a large distance. Furthermore, we were informed by a local resident that the simulated debris that had most likely been released from a point off Miyako, Iwate on June was found washed ashore on the coast of Arch Cape of Oregon, U.S.A. as of March 18 (Mon) of this year, 1 year and 9 months after the release. The simulated debris released 20km off Miyako had drifted toward the east; its transmitter stopped sending signals at a distance of 2,500km from the release point because its battery ran out of power (in approximately 6 months), making it impossible to determine its location thereafter. The sinking rate (i.e., the percentage of debris volume that is beneath sea surface with respect to the total volume of the debris) was 35% and, on the basis of the results of the university s investigation at the Japanese sites with marine debris that drifted ashore, the items that sank at such a rate were refrigerators, containers, tires with wheels, shoes/sandals, Japanese-style beddings/floor cushions, and some plastic products. From the finding that the simulated debris that was released 3 months after the disaster for tracking of drift route has already drifted ashore, it can be presumed that the disaster-generated marine debris with similar sinking rates must have already been washed ashore, although with some uncertainties regarding the drift route and time as mentioned above. This finding partly 36

41 supports the drift route prediction released by the MOE. The reasons why no massive arrival of marine debris has been reported from the expected places of arrival may be partly because of the following: (1) much of the debris cannot be determined whether they are disaster-generated or not, (2) marine debris is dispersed widely in the ocean, and (3) much debris remains in the ocean and the amount of debris that actually become washed ashore on coasts is not necessarily large. 4. Secondary Disaster Caused by the Tsunami-Generated Marine Debris As the marine debris was generated by the massive energy of tsunami, they can have various properties that are different from those of marine debris generated under ordinary situations. For example, drifting of houses and cars can occur, causing the following major secondary disasters: 1) Loss of the function of a harbor due to it being blocked 2) Problems in maritime navigation due to accidents such as collision of a ship against marine debris and entanglement of the debris with the propeller of the ship 3) Problems in fishery such as fishing boat navigation and seine fishing and damage to aquaculture facilities 4) Decrease in fishery resources caused by destruction and change of fishing environment 5) Adverse effects on tourist facilities/industry caused by damage to sceneries and disturbed use of coasts because of drifted debris 6) Increased psychological stress on residents caused by drifted toxic waste and debris of unknown content 7) Adverse effects on marine and coastal organisms that may be caused by accidental ingestion of marine debris and entanglement with fishing nets Although these events can be caused by marine/drifted debris that are generated under ordinary situations, once a massive amount of marine debris is generated by disasters such as a tsunami, a large amount of drifted debris is expected, which even increases the risk of the above-mentioned events to occur. From the results of investigation in Japan, a number of actual cases of Items 1) to 5) secondary disasters have been confirmed. On the other hand, no clearly identifiable cases of Items 6) and 7) secondary disasters have been found. However, regarding Item 6), medical wastes such as injectors, sample bottles with blood inside, and containers with toxic waste were often reported washed ashore in many places in the past; they may cause a non-negligible problem if they are also found this time. With regard to Item 7), many studies and surveys on the adverse effects on marine and coastal organisms have been carried out overseas and results have been reported. However, in Japan, the number of such studies whose achievements have been reported still remains small. 37

42 As one of impacts on other countries, problems have arisen concerning the drifting and arrival of floating piers from the Misawa Fishing Port. There is also a risk that large marine debris, such as the unmanned ship drifting off the coast of Canada, may collide with other ships. In addition, there is also a problem regarding its demolition. However, in the case of small marine debris, as it most likely tends to disperse in the ocean during the course of its drifting, the risks of Items 1) to 3) should generally decrease with time. As the U.S. side expressed at the meeting of U.S.-Japan NGOs, Items 4) to 7) will draw increasing attention as future problems to be addressed. In particular, in connection with accidental ingestion of marine debris by marine and coastal organisms, the problem of generation of fine particles due to the degradation of materials such as plastics during the course of their drifting has been pointed out. As a problem on plastics that was reported by the Algalita Marine Research Institute and others, degraded plastics have been found in the stomach of myctophidae (plankton-eating fish) and other fish caught in the North Pacific Central Gyre. The percentage of fish that have ingested plastics amounted to 35% of the total number of fish examined, confirming the problem posed by plastic plankton [4]. Although these may not be the problems specific to disaster-generated marine debris, attention needs to be paid in future to how to address these problems. 5. Future Problems to Be Addressed In Oregon, a cooperative system has been established by the U.S. and Japanese NGO groups in order to identify whether the characters on the marine debris found in clean-up activity are Japanese. However, no massive arrival of disaster-generated marine debris from Japan had been identified during the ICC performed globally in September As for information on the properties and characteristics of disaster-generated marine debris obtained from our field surveys of sites in Japan where marine debris from the March 11, 2011 tsunami arrived, we would like to disclose them on the university s website to domestic institutions (e.g., universities concerned, NGO groups such as JEAN) as well as overseas institutions (public organizations such as NOAA, research institutes such as universities, NOG groups such as Ocean Conservancy). While sharing relevant information with these parties, we will make efforts to lessen worries about the disaster-generated marine debris among people in the areas where secondary disaster is anticipated to occur. In the university s research, different sets of simulated debris (to each of which a transmitter was attached) were released off the coast of Tohoku in October 2011, January 2012 and January 2013, to identify their drift routes. A total of 14 sets of simulated debris (with improved battery lifetime of 3 to 5 years) excluding those having been drifted ashore within Japan are still now drifting in the ocean. As for these sets of simulated debris, we intend to obtain and disclose on the university s website the actual data as to whether they will drift ashore in a coastal area of the North American Continent or in an area of minor islands such as Hawaii, or whether they 38

43 will drift to the Great Pacific Garbage Patch, where the majority of marine debris is said to remain accumulated. At the symposium held in the university, plastics contained in marine debris were pointed out to pose the largest problem because of their long-term effects on the environment and living organisms as they degrade into fine particles. As the occurrence of secondary disasters mentioned above will vary depending on the actual destination of the disaster-generated marine debris, we will continue to track such debris, while carrying out the study of their long-term effects in the field. (References) [1] Results of investigation on marine debris generated from the Great East Japan Earthquake jointly conducted by the U.S. and Japanese NGO groups and domestic provision of information, JEAN, February 2013 [2] Publication of results of drift route prediction of marine debris generated from the Great East Japan Earthquake, Office of Marine Environment, Water Environment Division of Environmental Management Bureau, the Ministry of the Environment, April 2012 (In Japanese) [3] Publication of intermediate results of drift route prediction of marine debris generated from the Great East Japan Earthquake, Office of Marine Environment, Water Environment Division of Environmental Management Bureau, the Ministry of the Environment, November 2012 (In Japanese) [4] Plastic ingestion by planktivorous fishes in the North Pacific Central Gyre, Christina M. Boerger et. al., Marine Pollution Bulletin, 60 (2010),

44 Chapter 5 Discussion on Method to Estimate Amount of Marine Debris Generated 1. Estimation Method Based on Floor Area of Disaster-Stricken Buildings In the Damage estimation of the Nankai Trough massive earthquake (Phase 1 report) (August 29, 2012) prepared by the Central Disaster Prevention Council, the number of totally collapsed buildings due to tsunami was estimated by assumed disaster damage type and by prefecture. On the basis of this number of totally collapsed buildings and the total number of buildings in each prefecture, percent damage was calculated by disaster damage type. As for the total floor area of each prefecture, data are available in the report of Investigation Commission on the Building Stock Statistics (Ministry of Land, Infrastructure, Transport and Tourism, March 2010), which provides data by residential/nonresidential building and by wooden/nonwooden building. Furthermore, data of the total floor area of public nonresidential (national/local government) buildings by prefecture are available. Assuming that all the public nonresidential buildings are nonwooden, the gross floor area by structure type was calculated for each prefecture. Furthermore, assuming that the percent damage is the same regardless of structure type and by multiplying the gross floor area by structure type by percent damage, we calculated the damaged floor area by structure type for each prefecture. Then, by multiplying this value by the debris generation basic unit by structure type and by rubble type, we estimated the amount of rubble generated for each prefecture. 2. Estimation Method Based on the Number of Damaged Buildings The 2008 Housing and Land Survey (Statistics Bureau) lists the number of houses by prefecture and structure type (wooden type, wooden and fire-proofed type, steel-framed reinforced concrete type, steel-framed type and others). However, because the numbers of houses by structure type are based on a sampling survey, their sum does not match the total number of houses in each prefecture. Therefore, for each prefecture, by dividing the total number of houses by the sum of the numbers of houses by structure type, we calculated the compensation coefficient for the number of houses. By multiplying the number of houses by structure type of each prefecture listed in the Housing and Land Survey by this compensation coefficient for the number of houses, we calculated the adjusted number of houses by structure type. This was then added to the number of corporate buildings by structure type (wooden type, steel-framed reinforced concrete type, reinforced concrete type, steel-framed type, concrete block type, and others) listed in the 2008 Corporate Buildings Survey (Statistics Bureau), and the number of buildings by structure type was calculated for each prefecture. For this purpose, the types of buildings were categorized into 4 types (wooden type, RC type, steel-framed type, and others). 40

45 The rest of the process to estimate the amount of rubble generated is the same as in the method based on floor area of disaster-stricken buildings. 3. Verification of Methods to Estimate Amount of Disaster Waste Generated As for the buildings damaged by the Great East Japan Earthquake, the Disaster Countermeasures Office of the Fire and Disaster Management Agency announced the number of damaged residential buildings determined by dividing them into totally collapsed buildings, half-collapsed buildings, partially damaged buildings, inundations above floor level, and inundations below floor level. By applying this number of totally collapsed buildings, we estimated the amount of rubble generated from the Great East Japan Earthquake in the three prefectures of Iwate, Miyagi, and Fukushima and compared the results with the estimated amounts of generated rubble prepared by the MOE to verify the effectiveness of the above methods. Table 5-1 Percent damage of each prefecture by the Great East Japan Earthquake Prefecture Number of buildings Number of Total No. of houses Total No. of corporate buildings Total No. of buildings totally collapsed buildings Percent damage (%) Iwate 550,000 10, ,890 19, Miyagi 1,014,000 15,000 1,029,000 85, Fukushima 808,000 14, ,920 20, Table 5-2 Estimated amount of generated rubble for each prefecture (Based on damaged floor area) Prefecture Structure type Damaged floor area (m 2 ) Waste wood Basic unit (t/m 2 ) Concrete Waste metal Others Waste wood Amount of generated rubble (1,000 tons) Concrete Waste Others Total metal Iwate Miyagi Wooden 2,242, Nonwooden 1,020, , ,109 Subtotal 190 1, ,809 Wooden 6,710, ,094 Nonwooden 4,615, , ,017 Subtotal 598 5, ,110 Wooden 2,088, Nonwooden Fukushima 1,195, , ,300 Subtotal 181 1, ,951 Total of three prefectures 969 7, ,610 10,870 41

46 Table 5-3 Estimated amount of generated rubble for each prefecture (Based on the number of damaged buildings) Prefecture Structure type Number of damaged buildings Basic unit (t/building) Amount of generated rubble (1,000 tons) Waste wood Concrete Waste metal Others Waste wood Concrete Waste metal Others Total Iwate Wooden 16, RC 2, Steel-framed Others Subtotal ,115 Miyagi Wooden 56, ,660 RC 22, , ,260 Steel-framed 5, ,119 Others Subtotal 783 6, ,042 Fukushima Wooden 16, RC 3, Steel-framed 1, Others Subtotal 199 1, ,489 Total of three prefectures 1,147 7, ,230 10,647 As a result of estimation using the above two methods, we obtained the rubble amounts of 10,870 thousand tons when based on the damaged floor area and 10,646 thousand tons when based on the number of damaged buildings. In either case, the amount was nearly equal to 43% of the estimated figure of MOE, that is, 24,869 thousand tons. The reason for this discrepancy is that the totally collapsed buildings alone were included in the source of rubble generated. In order to compensate for this discrepancy, we can assume that the amount of rubble generated from two half-collapsed buildings is equal to that generated from one totally collapsed building. Therefore, we added 1/2 of the total number of half-collapsed buildings to the total number of totally collapsed buildings for each prefecture, thus adjusting percent damage. When percent damage was adjusted by this method, the values for Iwate, Miyagi, and Fukushima became 3.87%, 15.66%, and 6.83% respectively. Using this method, we estimated the total amounts of rubbles generated from three prefectures as 20,748 thousand tons based on the damaged floor area and 20,476 thousand tons based on the number of damaged buildings, which were about 83% of the amount estimated by MOE. Using the compensation method in which we added one-half of the total number of half-collapsed buildings to the total number of totally collapsed buildings, we were able to obtain increased reproducibility of the amount estimated by MOE. In particular, high reproducibility was obtained for the rubble amount generated from Miyagi by estimation based on the number of damaged buildings. Table 5-4 Comparison of estimated results (After compensation for percent damage) Prefecture Estimation by MOE Estimation based on damaged floor area Amount Percent damage Amount Percent damage generated (%) generated (%) (1,000 tons) (1,000 tons) Estimation based on No. of damaged buildings Amount Percent damage generated (%) (1,000 tons) Iwate 6, , , Miyagi 15, , ,

47 Fukushima 2, , , Total of three 24, , , prefectures 4. Future Tasks to Be Addressed 4-1. Examination of Basic Unit In a method using a basic unit as was examined here, a large difference in result may occur depending on the setting of the basic unit. As a future task, it is necessary to collect data based on actual records of the Great East Japan Earthquake and to set an appropriate basic unit. Furthermore, as the criteria for evaluating the adequacy of an estimation method, we used the estimated figures prepared by MOE. However, these estimated figures in themselves need to be re-examined for adequacy Examination of Compensation Coefficient for Percent Damage In this chapter, on the basis of the estimated figures for the total number of totally collapsed buildings due to the tsunami, we examined the introduction of the compensation coefficient for percent damage to the estimation of the amount of generated rubble by also including half-collapsed buildings. As a result of this introduction to the estimation based on the number of damaged buildings, we were able to obtain the amount of rubble generated from Miyagi that was close to the figures estimated by MOE. Then, we recalculated by introducing the same compensation coefficient for percent damage (1.89) into the estimation for the three prefectures of Iwate, Miyagi, and Fukushima. From this recalculation, we were able to obtain increased reproducibility of estimation for Fukushima based on the number of damaged buildings (2,813 thousand tons as against 2,876 thousand tons estimated by MOE) (See Table 5-5). Thus, it is worthwhile to examine the introduction of the compensation coefficient for percent damage (1.89) into the estimation of amount of rubble generated from the tsunami that may occur following a possible Nankai Trough massive earthquake for all damaged prefectures. However, even with this compensation coefficient for percent damage, the figure estimated by MOE cannot be reproduced well for the amount of rubble generated from Iwate. It is necessary to identify the cause of this discrepancy by also reviewing the adequacy of MOE s estimation. Table 5-5 Comparison between figures estimated by MOE and those estimated using compensation coefficient (1.89) for percent damage for three prefectures Prefecture Estimation by MOE Estimation based on damaged floor area Amount Percent damage Amount Percent damage generated (%) generated (%) (1,000 tons) (1,000 tons) Estimation based on No. of damaged buildings Amount Percent damage generated (%) (1,000 tons) 43

48 Iwate 6, , , Miyagi 15, , , Fukushima 2, , , Total 24, , , Examination of Debris Run-off Percentage Our research in this fiscal year has covered up to the examination of a method to estimate amount of rubble generated from structures such as houses. According to the estimation method of MOE, in order to obtain the amount of run-off into the ocean, the amount lost by fire is subtracted from the amount of rubble generated and the remainder is multiplied by the debris run-off percentage. Furthermore, the result after subtracting heavy rubble such as concrete from this amount of run-off is equal to the amount of marine debris. However, the debris run-off percentage estimated by MOE differs considerably among Iwate (30%), Miyagi (7%), and Fukushima (42%). It is necessary to investigate the cause of these differences. Furthermore, on the basis of the investigation results, it is necessary to identify a method to set an appropriate run-off percentage that can reflect regional characteristics Disaster Debris Other Than Those of Houses In our research for this fiscal year, we focused our examination on the amount of rubble generated from houses and others. In addition to these, following the tsunami after the Great East Japan Earthquake, many kinds of marine debris were generated such as cars, driftwood from coastal sand-erosion control forests, ships, aquaculture facilities, fixed fishing nets, and containers. As the actual amount of such debris generated can vary depending on regional characteristics, it is necessary to determine a method of estimating the amount of such debris generated that can reflect regional characteristics. 44

49 Research Presentation, etc. (Oral Presentation, etc.) 1. Haruo Matsumura, Measures to Promote Collection/Disposal of Debris at the Sea Bottom, Symposium of Tottori University of Environmental Studies (2012) 2. Koki Nishizawa, Drift Route Prediction of Simulated Debris with Transmitters, Symposium of Tottori University of Environmental Studies (2012) 3. Haruo Matsumura, Koki Nishizawa, Shin Sato, Research Study on Marine Debris, International Symposium of Tottori University of Environmental Studies (2012) 4. Shin Sato, Secondary Disaster Caused by Marine Debris Generated from the Massive Tsunami Following the Great East Japan Earthquake, The 34th Annual Meeting of Japan Waste Management Association (2013) 5. Masaru Tanaka, Koki Nishizawa, Makoto Okazaki, Tomomichi Kobayashi, Haruo Matsumura, Tetsuji Arata, Shin Sato and Yasuhiko Kagami, Tracing Drifting Paths of Tsunami Debris Using Mock Debris Attached with Transmitters, 12th Expert Meeting on Solid Waste Management in Asia and Pacific Islands (SWAPI) in Tokyo, Japan (2013) (Submitted manuscript, etc.) 1. Masaru Tanaka and Koki Nishizawa, Study on Tsunami Debris Drifting Paths Using Mock Debris Attached with Transmitters, The International Solid Waste Association (ISWA) report (2013, in preparation for publication) (Acquisition of intellectual property right) None 45

50 Illustration of Research Outline Run-off of disaster-generated marine debris into the ocean Disaster prevention Information network Occurrence Prediction and analysis Information sharing Drifting of disaster-derived debris Examination of prediction method for amount of rubble generated Past cases, methodology, etc. Hokkaido Hawaii Adverse effects on maritime navigation, industrial activity, and living environment Risks of secondary disaster Investigation of damage situations and sources of rubble generated Basic research for prevention of secondary disaster Simulation Release of simulated debris Satellite data analysis Visual inspection Debris collection/inspection Identification of drift route Investigation and analysis of actual data for identification of marine debris K Research on Prevention of Secondary Disaster by Investigation of Drift Routes of Marine Debris Generated from the Tsunami Following the Great East Japan Earthquake 46