[S23-P] Poster

[S23-P-11] Integrated Probabilistic Tsunami Hazard Assessment against possible tsunamis along Nankai Trough, Sagami Trough, and Japan Trench

^○Kenji Hirata¹, Hiroyuki Fujiwara¹, Hiromitsu Nakamura¹, Masaki Osada¹, Tsuneo Ohsumi¹, Nobuyuki Morikawa¹, Shin'ichi Kawai¹, Takahiro Maeda¹, Hisanori Matsuyama², Nobuhiko Toyama², Tadashi Kito², Yo'ichi Murashima³, Yasuhiro Murata³, Takuya Inoue³, Ryu Saito³, Shin'ichi Akiyama⁴, Mariko Korenaga⁴, Yuta Abe⁴, Norihiko Hashimoto⁴, Tomoya Hakamata⁴ (1.NIED,Tsukuba,Japan, 2.OYO,Tsukuba,Japan, 3.KKC,Tokyo,Japan, 4.CTC,Tokyo,Japan)

Last years, we presented regional Probabilistic Tsunami Hazard Assessments (PTHAs) for three coastal zones along Nankai Trough, Sagami Trough, and Japan Trench (Hirata et al., 2014, 2015, AGU; Hirata et al., 2016, SSJ). In three PTHAs, our procedures are follows; (i) we consider all possible earthquakes in the future, including those that the Headquarters for Earthquake Research Promotion (HERP) of Japanese Government already assessed. (ii) We construct a set of Characterized Earthquake Fault Models (CEFMs), for all the possible earthquakes(Toyama et al., 2014, JpGU; Korenaga et al., 2014, JpGU). (iii) For all the CEFMs, we compute tsunamis by solving a nonlinear long wave equation, using FDM, including runup calculation, over a nesting grid system with a minimum grid size of 50 meters. (iv) Finally, we gather excess probabilities for variable tsunami heights, calculated from all the CEFMs, at every observation point along the coastal zone to get PTHA. We incorporated aleatory uncertainties inherent in tsunami simulation and earthquake fault slip heterogeneity in the integration process(Abe et al., 2014, JpGU).
In this study, we integrate three of the regional PTHAs calculated from all possible earthquakes along Nankai Trough, Sagami Trough, and Japan Trench to get a nationwide PTHA. We will make two kind of the probabilistic tsunami hazard map; one is “Present-time hazard map" under an assumption that earthquake occurrence basically follows a renewal process based on BPT (Brownian Passage Time) distribution. The other is “Long-time averaged hazard map" under an assumption that earthquake occurrence follows a stationary Poisson process. A Present-time hazard map, showing the probability that the tsunami height will exceed 5 meters at coastal points in next 30 years (starting at 1st January, 2016), suggests high possibility over 50% along the southern coasts of Shikoku to Tokai region, perhaps due to contribution from the next Nankai earthquake.