The 2011 Tohoku-oki earthquake ruptured a vast plate boundary area of about 500 km x 200 km, resulting in a slip of about 50 m near the trench. The reasons for such large slip include the fact that the slip penetrated the trench, the occurrence of the thermal pressurization, and small elastic constants in the shallow part. The reasons for the vast slip area can be explained by a hyper asperity model as well as a large strong patch model. The reasons why we could not foresee such a huge earthquake can be summed up in one sentence: we “overlearned” from the limited information we had. It is vital to learn from the Tohoku-oki earthquake, but we should not overlearn from it. Otherwise, the next M9 earthquake will be an “unexpected earthquake” again.

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The achievements of the “Nankai Trough Wide Area Earthquake Disaster Prevention Research Project” commissioned by MEXT started in 2013 are described here. In the field of disaster prevention, lessons learned from the 2011 Great East Japan Earthquake damage, estimation with different spatiotemporal scales, and a preliminary reconstruction plan based on future spatiotemporal changes in the social environment were studied. They were integrated through workshops and utilized to promote the information dissemination by regional study groups using the disaster scenarios and disaster information platform. In the field of survey, observation, and simulation research, the seismic image on the Nankai trough with threedimensional seismogenic zone structure and evaluation of earthquake occurrence diversity based on advanced simulation research, tsunami history surveys, and historical literature surveys were researched. As the result, the basic system of transition prediction was obtained.

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We practiced disaster prevention education using regional information by Geographical Information System (GIS) as a unit of “Natural blessings and disasters”of the third grade of lower secondary school “science” In addition, after practicing the classes, we released from the Internet to students'guardians both outline of this disaster prevention education and regional information on disaster prevention. This class practice showed that the use of regional information through GIS (map information) was effective in improving students'interest in and understanding of natural disasters. From the results of the questionnaire to the guardians, the published content was highly evaluated. It was also found that such attempts contribute to the improvement of opportunities to discuss natural disasters at home.

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This study focuses on governance over trans-boundary volcanic disaster. By analyzing policy decision making processes relating to international air traffic disturbances caused by 2010 Icelandic volcano Eyjafjallajökull eruption, it tries to describe characteristics of global disaster governance. The 2010 volcanic eruption caused airport closures or flight cancelations in Europe which resulted in huge socio-economic damages. In order to solve the problem, scientific data, such as changes in volcanic activities, prediction of volcanic ash dispersion or volcanic ash concentration were required for adequate policy making. This means that a disaster response for trans-boundary volcanic disasters needs a different approach from that for other disasters which requires humanitarian assistance coordination. What is more, the scientific data defining the policy making were uncertain in 2010, which made the decision making more difficult. This event has triggered the emergence of new disaster risk governance, which is based on self-sustaining and decentralized development of scientific platforms (epistemic communities) by scientists and public officers across countries and from different fields with a common purpose to solve problems.

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In disaster management, local governments are the principal actor to mitigate the damage as much as possible. During disaster management activities, staff of local governments learn know-how during disasters. This know-how is quite important for managing future disasters. However, the members of a division are usually changed once every several years. So, the system for sharing the experiences and know-how of disaster management is indispensable. In order to do level up the skill of a disaster management division, several seminars have been conducted by the central government. However, the number of these is limited due to budget. The knowledge and skills are not shared well because lack of communication. In this study, we propose an educational program, which firstly educates some staff as experts and the experts educate all the rest of the local staff. We started the program in April 2019. This system enables education in a local government system.

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We developed a victim data base (“1999-2018”) for heavy rainfall disaster events in Japan from 1999 to 2018, and 1259 victims were classified. The purpose of this study is to analyze the characteristics of victims caused by heavy rainfall disaster by typhoon No.1919 (“T1919”) in comparison with “1999-2018”. Through this heavy rainfall event, 88 people were killed or missing in western Japan. Characteristics of victims by ““T1919” were as follows: 1) 72% of the victims were death by flood disaster. This is the highest ratio for heavy rainfall disaster events since 1999. 2) 58% of victims died outdoors. 54% of them died while driving their car. This is the highest ratio since 1999. The danger of outdoor activities in heavy rain was shown again. 3) 66% of the victims due to flood disaster died near the flood disaster hazard area. The ratios is higher than “1999-2018”. 93% of flood victims died in potentially flooded lowlands. This ratio is consistent with “1999-2018”. Understanding for hazard map information is important for the disaster prevention.

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Due to heavy rainfall caused by the Baiu- front, 24 hours of precipitation resulted in a record-breaking 400 mm of rainfall from noon of July 3, 2020, to noon on July 4, mainly within the Amakusa, Ashikita and Kuma Districts. This heavy rainfall made it impossible to record the water level after the 7:30 am water level of 12.88 meters on July 4 since it flooded the Watari Observatory in Kuma Village located at the mid-stream of the Kuma River. An intensive care home for the elderly in the Watari area, “Senjuen” is located in the lowlying area of floodplain, and according to the planned scale flood-hazard map, it is not in the inundation assumption area. However, when it comes to the largest-assumption scale floodhazard map, it could flood 10 to 20 meters. Thus, 14 residents died because the rapidly rising water level resulted in there not being enough time to evacuate the upper level of the building. The maximum height of inundation trace was recorded at 760 cm on the Mine community in the Watari area, and this aligns with the estimated inundation map of 8 to 9 meters that the Geographical Information Authority had predicted.

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