堤防を越えた津波（上）：発災要因として，広範囲・大規模に押し寄せた津波が重要である．第一説明者による岩手県宮古市撮影動画分析から，閉伊川河口では，引き波で地震発生31分後に約1 m水面が低下して川底の一部がみえていた．その後，押し波は，宮古湾から閉伊川を遡って水位を徐々に増加させ，地震発生37分後に3.5 m高の堤防（天端高約5 m (TP)）を越え，当時の市庁舎周辺の市街地を浸水させはじめた．津波は，市街地にさらに流れ込み，地震発生42分過ぎに最高水位（写真中央の堤防上で約7 m (TP)，写真左側の建物付近で約6 m (TP)）に達した．（宮古市，2011年3月11日撮影）
福島第一原子力発電所と周辺地（下）：福島第一原子力発電所事故で拡散した放射性物質の有害性が継続しており，福島県の災害構造は主として津波が発災要因であった岩手県等と異なる．原発（写真上）周辺数kmには，中間貯蔵施設があり，一般市民の立ち入りが禁止されている．福島県内から運ばれた放射能汚染物質入りのフレコンバッグ（黒色，写真下）や分別施設（白い建物，写真中央）等がみえる．原発から約4 km北に2020年9月開館の東日本大震災・原子力災害伝承館があり，その上空124 mからドローンで写真撮影．（瀬戸真之，2021年2月8日撮影）
When major natural disasters occur, not only scientific and national administrative parties but also individuals and organizations from the local areas affected by the disaster prepare a variety of reports. Considering the general structure of natural disaster processes that occur and progress in diverse and specific spatiotemporal conditions, such reports prepared locally are expected to contribute to both reminding residents of the disaster and to improving future hazard-mitigation measures of the area concerned. At the same time, being based on primary sources related to various hazard-triggered local events, the reports support a more comprehensive understanding of the disasters as a whole. This paper reviews numerous reports on major tsunami disasters that occurred on the Sanriku Coast, Northeastern Japan, since the late 19th century. Most reports on the 1896, 1933 and 1960 tsunami disasters were prepared by local intellectuals supported in some cases by local governments. After the 2011 tsunami, most stricken municipalities published reports with financial assistance from the national government, and some of them received reporting and editing assistance from outside experts, including scholars and journalists. As local reports are prepared in a situation of potentially plentiful primary sources related to various aspects of the disaster in the area, the results of such reports depend heavily on the collection and presentation of primary sources. Report writers, including outside experts, contribute to reporting, editing, and presenting using suitable images, maps, tables, and narratives. For more effective use of the primary sources, it is suggested that these people have an adequate perspective of both the overall structure of disaster processes and the local conditions of the area concerned.
Records describing past natural disasters are essential for promoting disaster prevention, because they can indicate the risk of disasters in a specific region at a specific time. The experience of the 2011 Great East Japan Earthquake was a lesson on the importance of recording and archiving all details of disasters. Since then, disaster archives have been created for the affected areas. Compilation of disaster archives is in progress for various natural disasters that occurred after 2011. Problems facing historical archives of tsunami disasters in the Sanriku coastal area are investigated and the contents required of future disaster archives are discussed. Records included in the study are as follows: images of disaster scenes and tsunami boulders after the 1896 Meiji Sanriku Tsunami, monument to the 1933 Showa Sanriku Tsunami, publications covering disasters, and disaster experience centers. Some archive facilities had to be closed due to changes in social conditions and some information records have become too weathered to decipher, which may prevent an understanding of the details of past disasters and lessons to be learned. Disaster records communicate the type and degree of damage at the time of a disaster and provide educational information. It is, therefore, important to preserve these records in perpetuity, while continuing to add new information and records.
Recently, a large number of natural disasters have occurred and many records of the disasters have been collected. Insufficiencies are confirmed in landform information contained in disaster records of local scale areas. In addition, various problems are clarified that relate to geospatial information that make it difficult to comprehend natural disasters graphically. In order to make it easier to understand natural disasters, it is necessary to convert original basic landform information into higher order information. To develop higher order landform information with information on materials, processes, and ages of local areas, an overlay is needed with geomorphological results provided as geospatial information on the latest basic landform information, while retaining a geomorphological perspective. In order to understand landform information of past disaster records, they also need to be reviewed using the latest analytical techniques and study results. In such a review, it is important to attempt a comprehensive interpretation, and to refer to records in many study fields. In the process of preparing higher order landform information, one problem is that local areas have unreliable information on natural disasters. To solve this problem, it is desirable that earth science and geography education activities are undertaken sufficiently so that residents can identify local landform information by themselves and, furthermore, that disaster prevention and disaster reduction enlightenment activities are developed. Even if higher order landform information is prepared, there is likely to be damage caused by natural disasters when administrative agencies and residents have a low awareness of the information. Therefore, it is believed that records of land-use changes associated with landform conditions and their recognition can prevent the activation of a normalcy bias resulting from a deterioration of disaster memory and a decline of disaster prevention consciousness, and can increase the effectiveness of disaster prevention and disaster reduction activities in the future.
In this study, evacuees' rosters and other relevant disaster records are used to geographically clarify the relationship between people's evacuation behavior following the Great East Japan Earthquake, social and demographic characteristics of evacuees, and housing damage caused by tsunami following the earthquake in Yamada Town, Iwate Prefecture. The trend of shelter entry and exit is analyzed on the basis of three scales. The first scale is the municipality unit; trends in the numbers of people entering shelters in Yamada Town are compared to those in other affected municipalities on the coast in Iwate Prefecture and regional differences in these trends are clarified. The second scale is the district or small area unit; regional differences in rates of entry to shelters in Yamada Town and factors affecting these differences are explained geographically. The third scale is the shelter level; regional differences in rates of entry to school shelters in small areas are analyzed in relation to evacuees at two elementary schools. Furthermore, regarding evacuees in a school shelter where a daily list is available, a logistic regression analysis is performed to explain evacuees' decisions on whether or not to stay in the shelter on the basis of variables such as gender, age, and family situation. The regression analysis for the first scale reveals that the decreasing trend in the number of evacuees in shelters in Yamada Town has been slow compared to those in other affected coastal municipalities. The study reveals that progress in the construction of emergency temporary housing is the factor with the greatest impact on an evacuee's decision to leave a shelter. Regarding the second scale, the geographical distribution of the number of shelter residents in Yamada Town is analyzed on the basis of the scale of a district and a small area. The analysis reveals that regional differences in shelter entry rate reflect social network, topographical features, and developmental process of the settlement. Regarding the third scale, the relationship between distance from the shelter and entry rate of affected households is analyzed by small area using the rosters of Yamada Minami Elementary School and Orikasa Elementary School evacuation shelters. A significant correlation is found between average road distance from Yamada Minami Elementary School and affected household entry rate, and it is observed that many residents were from areas located within 1 km from the school. On the other hand, no significant correlation is found between average road distance from Orikasa Elementary school and affected household entry rate. Regarding the Orikasa Elementary School shelter, almost daily entry and exit records could be obtained for the period from April 9, 2011 to August 3, 2011. Using this record, age and family composition of withdrawers during this period could be identified. A logistic regression analysis was performed with gender, age group, marital status, and family type as explanatory variables. With respect to the influence of a resident's age and family structure on his or her exit time, it is found that the withdrawal rate of residents aged 75 years or more was high until the beginning of May. Households that stayed in the shelter with 0 to 18-year-old juveniles tended to find it better to stay in the shelter until their children's schools reopened. After resumption of schools, at the beginning of April; however, they tended to leave in higher numbers. The study concludes that, although schools should support evacuees during the earlier period of an evacuation as large-scale evacuation shelters, various types of shelter should be developed and reorganized to suit the evacuees' needs in case the evacuation is extended for a long period.
Changes in commercial structure following the Great East Japan Earthquake Disaster are examined from organizational and spatial perspective. The study area is Yamada Town in Iwate Prefecture, Japan, which was severely damaged by the huge tsunami caused by the 2011 Great East Japan Earthquake. Supported by the municipality, three main actors—local minor retailers, local major retail companies, and major retailers outside the area—pushed through a restructuring of the commercial environment. Two commercial institutionalizing movements occurred during this process. One was led by a local major retail company, while the other was led by local small retailers with municipality support. In the case of Yamada Town, a local major retail company had a significant role in changing the commercial structure because of its financial power and human resources. This retailer established its business in local infrastructural facilities, including as temporary stores, and rapidly organized local retailers with its future business plans. In contrast, the municipality projects assumed a role in reconstructing the stores of other local retailers that had difficulty making management decisions about the future. Moreover, in suburban areas, local retailers supported residents. The spatial changes in the commercial structure may be understood from the perspective of regional structure, in terms of the central district, its suburban areas, and areas outside Yamada Town. The local retailers and the municipality organized a commercial hub in the central district. In addition, major retailers located large stores in suburban areas that were easily accessible. Moreover, large shopping centers in other cities exerted a commercial influence on all of Yamada Town. These results are evaluated from a geographical perspective to record and systematically analyze regional characteristics based on several spatiotemporal scales. It is necessary to describing the disaster recovery process in detail so that records of the event and its experience are preserved for future generations.
Using miscellaneous local reports on tsunami disasters and related subjects, the location/relocation histories of three settlements situated on the tsunami-prone mid-Sanriku Coast are retraced, and differences in the selective use of geomorphic resources by the settlements are discussed based on the retraced histories and original geomorphological investigations. On the coast, piedmont gentle slopes and small coastal lowlands have been generally used for the locations of fishing and farming settlements. Of course, coastal lowlands provide the settlements with convenient location for both fishing and farming activities, but they are very sensitive to tsunami hazards, while piedmont gentle slopes adjacent to the lowlands are almost free from tsunami. Although the undulating surface forms of piedmont gentle slopes requires artificial transformation for the use as flat housing lots, the transformation works were not so hard even when earthmovers were not available, because they are composed of unconsolidated rubbly deposits or grus, which are the products of morphogenetic processes under changing climatic and sea-level conditions since the mid-Pleistocene in the zone of granitic rocks. Three neighboring coastal hamlets, Oura, Funakoshi, and Tanohama, suffered repeated tsunami hazards in 1896, 1933, 1960, and 2011. Oura continued to be located on near-coast piedmont gentle slopes for more than 150 years with the additional use of adjacent coastal lowlands as paddy fields. Funakoshi moved from the beach to adjacent piedmont gentle slopes after the severe damage caused by the 1896 tsunami with continuing to use lowlands behind the beach as wet paddies. Tanohama, also damaged severely by the same tsunami, rejected the relocation from beach to the land prepared artificially on adjacent piedmont gentle slopes after the tsunami, and used the prepared land not for dwelling but upland farming. After the 1933 tsunami, which damaged Tanohama again, it moved to the already-prepared land, but many houses were built again on the beach and suffered damage from the 1960 tsunami. During the 2011 tsunami, both total number and ratio of damaged houses were highest in Tanohama and were rather low in the other two hamlets. Inhabitation in the lowland was legally prohibited after the 2011 tsunami and new public housing lots were constructed on piedmont gentle slopes around the existing settlements. The three hamlets thus showed differential location/relocation behavior to the same tsunami hazards and differential selection in the use of two-types of landform for dwelling, fishing, and farming. This was the result of a different cognition or evaluation of given geomorphic resources by the respective hamlets under respective living conditions. Cognition is interpreted as being highly influenced by the proportions of fishing and farming in livelihood, as well as changing contents of fishing, in each tsunami-sensitive hamlet. After the 2011 tsunami, all the three hamlets are located on the piedmont gentle slopes under the new regulation. Follow-up observations of newly constructed housing sites with transformation of piedmont gentle slopes are required to further understanding of the use of geomorphic resources under the changing living conditions of the hamlets.
As part of the recovery and reconstruction efforts following the Great East Japan Earthquake that occurred on March 11, 2011, at least two directions based on the conventional “record of disasters” are being pursued to identify the magnitude of disaster damage. The first is called “disaster archives,” which are detailed records of the disaster process in smaller areas and on a personal scale. The second direction aims to quantitatively measure the degree of subsequent recovery and restoration progress based on objective information including statistics. Various entities including the national government, local governments, and private research institutions are carrying out the latter efforts. Policy implementations following “evidence-based policymaking” (EBP) are also regarded as essential in recovery and reconstruction after severe earthquake disasters. To implement EBP-based recovery and reconstruction efforts after wide-area disasters of extreme severity, it is crucial to understand individual situations in the afflicted areas using local data retained and provided by respective municipalities. It is equally important to obtain and organize information on broader-area conditions—such as the conditions of the entire area of East Japan—through statistical data. In this paper, we examine the case of the Great East Japan Earthquake to describe the challenges faced in EBP-based recovery and reconstruction policy implementation and to offer strategies to overcome these issues. We found that the problem lies in how to collect, provide, and utilize necessary data for recovery and reconstruction policies. It is also indispensable to develop new indexes to measure the states of reconstruction based on outcome and to prepare rules and systems for collecting necessary statistical data throughout the post-disaster recovery and reconstruction stage. The issues that emerged through our study should be adequately considered and recorded as lessons to effectively plan, draft, and implement EBP-based policies during future recovery and reconstruction efforts following major disasters.
The 2011 Fukushima Daiichi Nuclear Power Plant Accident, caused by a Mw 9.0 earthquake and accompanying tsunami, triggered a discharge of radioactive materials and a mass evacuation of residents of Fukushima Prefecture. The evacuation is still ongoing and is eroding the local community. For posterity, it is necessary to archive memories and lessons from the affected area. To this day, the Fukushima prefectural government and Fukushima University are collecting damaged materials as part of efforts to build a nuclear hazard archive in Fukushima. The value and meaning of damaged materials and the aim of building a nuclear hazard archive are considered. Damaged materials are found to have investigative and educational value, and a nuclear hazard archive will provide a record of the region before and after the nuclear accident in Fukushima.