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[P-14] Making use of uncertain earthquake forecast information: Challenges toward disaster risk reduction against the anticipated Nankai Trough Earthquake (M8-M9), western Japan

*Yo Fukushima¹, Hiroaki Maruya¹, Makoto Okumura¹, Motoyuki Kido¹, Natsuko Chubachi¹, Ryota Hino¹, Kanan Hirano¹, Shunichi Koshimura¹, Miwa Kuri², Shuji Moriguchi¹, Yusaku Ohta¹, Hiroyuki Sasaki¹, Motoaki Sugiura¹, Tetsuya Torayashiki³, Fumihiko Imamura¹ (1. Tohoku University, 2. Japan Meteorological Agency, 3. Disaster Reduction and Human Renovation Institution)

Keywords:Nankai Trough Earthquake, Planning, Preparedness, Countermeasures, Tsunami

In western Japan, great earthquakes of M8-M9 are anticipated along the Nankai trough subduction zone (hereafter called the Nankai Trough Earthquakes), with 30-year probability of 70-80% (The Headquarters for Earthquake Research Promotion of Japan, 2019). The Central Disaster Management Council of the Cabinet Office, Government of Japan, updated the master plan on the promotion of the countermeasures against the Nankai Trough Earthquakes in May 2019 in such a way that the central and local governments as well as other institutions should react appropriately when the “Nankai Trough Earthquake Special Information” is issued. The local governments, public institutions and some private companies are supposed to update their countermeasure plans to be compatible with the master plan of the government. The “Special Information” is issued by the Japan Meteorological Agency when the probability of the occurrence of a Nankai Trough Earthquake becomes higher than normal.

Effective usage of such uncertain forecast information for disaster mitigation is challenging. To overcome this problem, we are developing a package of materials/tools that can help the organizations make effective plans. The core components of the packages are: 1) earthquake risk visualization tool considering various earthquake scenarios, and 2) recommended countermeasure recipes that provide check-up lists and countermeasure options for different sectors at different stages (e.g., immediate response, within one week, etc.). As for the risk visualization, we mainly deal with the tsunami inundation risk, which is the largest threat in terms of the number of anticipated victims, by considering an ensemble of inundation simulations of numerous fault models. We also investigate the societal response to the forecast information issuance for pursuing an integrated and mutually consistent set of recipes for global minimization of social disorders.