[in Japanese]

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This paper reports on content analysis of tweet data tagged with“# Rescue”in the 2018 West Japan Heavy Rain disaster compared with the case of 2017 North Kyushu Heavy Rain disaster. The results are summarized as follows. 1) There were no more than 16.5 % tweets which were described place name, number of people and their situation etc. of 2,171 tweets tagged with“# Rescue”. 2) Almost of the tagged tweets consisted of news articles and messages about introduction how to the“# Rescue”and encouragement to survivors sent Twitter users out of heavy rainy areas. In conclusion, rescue requests by“# Rescue”tweet increased of two times the rate of the 2017 rain disaster, and media coverage decreased. On the other hand, Twitter users outside of affected areas should decline sending tweets.

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While agent simulation has been used to investigate evacuation scenarios, evacuation speed of frail elderly has not been fully studied yet. Therefore, in order to obtain the evacuation speed of the frail elderly we recorded videos of evacuation drills held in a group home with care. We analyzed evacuation steps in detail through the videos and acquired the evacuation speed of the frail elderly. We also simulated the evacuation drills with an agent model using the observed data. In the simulation result, the evacuation completion time was about 10% faster than the measured time of the evacuation drills. The difference in evacuation completion time can be explained considering the time taken for “unplanned behavior” of caregivers such as stopping to think about the next action.

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If large scale earthquakes occur along the Nankai Trough, all residents living along the coast need to immediately evacuate after the earthquake for a period of several days due to the risk of tsunami from secondary quakes wiping out coastal communities. Although going out of the inundation zone is the best way to evacuate from the tsunami damage, sometimes it might be difficult because of topographic condition, handicap, blocked routes by destructed buildings. In order to expand capacity for evacuation from tsunami in the coastal areas, we should make several options of evacuation places and routes. In this study, firstly the current preparation situation for tsunami evacuation building was investigated. In order to explore the capacity for evacuation from tsunami in the community, we proposed workshop to discuss how to increase tsunami evacuation buildings, which should be certainly available by people in the community.

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This study proposed a method to estimate tsunami source models based on the thickness distribution of tsunami deposits. We applied the previously-proposed Conical Fault Models as tsunami source, which considers known data of inter-plate coupling and distribution of historical earthquakes. We further proposed a new method to calculate deposition volume along survey transects, and formulated the relationship between the fault slip and the deposition volume. To validate the new method, we estimated a tsunami source model of the 2011 Tohoku-oki Earthquake (Mw 9.0) based on the data of tsunami deposits from three areas. The fault slip was in a proportional to the deposit volume, and the magnitude was estimated at close to Mw 9.0. Therefore, it was revealed that the moment magnitude of the source model of a large tsunami can be estimated from only the thickness information of the tsunami deposits.

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