平成30（2018）年度　一般研究１実施報告書

課題番号	30−共研−1001	分野分類		統計数理研究所内分野分類		a
				主要研究分野分類		1
研究課題名	高解像度の地震活動確率予測モデルの開発
フリガナ 代表者氏名	ジュアン ジャンカン 庄 建倉		ローマ字		Zhuang Jiancang
所属機関	統計数理研究所
所属部局	モデリング研究系
職　　名	准教授

研究目的と成果（経過）の概要

We aim to analyze the seismicity in the Kanto region by fitting the 2-D-epicentre and 3D-hypocentre ETAS models to the JMA catalogue for events above magnitude M4.0. In the 3-D ETAS model, the focal depth is assumed to follow the beta distribution. Compared with results from the 2-D-epicentre ETAS model, the 3-D ETAS model greatly improves the data fitting. In addition, the stochastic reconstruction method is used when validating the results of the 3-D ETAS model, with results indicating that the shallow events are more productive and their aftershocks decay slightly faster in the time and epicentre dimensions. We also study the changes of seismicity patterns before and after the 2011 Tohoku earthquake. The direct aftershocks of events from the post-Tohoku period are more diffusive in time and epicentre but more concentrated in depth. The seismicity rate increases significantly following the Tohoku earthquake, especially along the interface of the subducting Pacific plate. The curve of cumulative background probabilities for events above M4.0 implies that the background rate decays back to the pre-Tohoku level in about 5 yr after the Tohoku earthquake. However,
the occurrence rates of smaller events (from M2.0 to M4.0) indicate that the adjustments of local stress field continue at finer scales. Finally, it is found that the 3-D model can reproduce the focal depths better than the 2-D model and improve the forecasting performance.

当該研究に関する情報源（論文発表、学会発表、プレプリント、ホームページ等）

Guo, Y., Zhuang, J. and Hirata, N. (2018). Modeling and forecasting 3D-hypocenter seismicity in the Kanto region, Geophysical Journal International, https://doi.org/10.1093/gji/ggy154, Vol.214, Issue1, pp.520-530, July 2018. (Published 17 April 2018)

Guo, Y.*, Zhuang, J., Hirata, N. and Zhou, S. (2018). Heterogeneity of Direct Aftershock Productivity of the Mainshock Rupture, 2018 Fall Meeting of the American Geophysical Union(AGU), Walter E. Washington Convention Center, Washington,DC, U.S.A., 14 December 2018. (Oral)

Guo, Y. (2018). Modelling and forecasting three-dimensional-hypocentre seismicity in the Kanto region, 2018 Japanese Joint Statistical Meeting, Chuo University, Korakuen Campus, Bunkyo-ku, Tokyo, Japan, 13 September 2018. (Oral)

研究会を開催した場合は、テーマ・日時・場所・参加者数を記入してください。

Not applicable.

研究参加者一覧
氏名	所属機関
郭 一村	東京大学