日本地球惑星科学連合2023年大会

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[J] オンラインポスター発表

セッション記号 S (固体地球科学) » S-TT 計測技術・研究手法

[S-TT44] 最先端ベイズ統計学が拓く地震ビッグデータ解析

2023年5月22日(月) 10:45 〜 12:15 オンラインポスターZoom会場 (6) (オンラインポスター)

コンビーナ:長尾 大道(東京大学地震研究所)、加藤 愛太郎(東京大学地震研究所)、矢野 恵佑(統計数理研究所)、椎名 高裕(産業技術総合研究所)

現地ポスター発表開催日時 (2023/5/21 17:15-18:45)

10:45 〜 12:15

[STT44-P03] Forecasting Aftershocks Immediately After the Large Main Shock with Epidemic-type Aftershock Detection Function

*森川 耕輔1長尾 大道2,3平田 直4,2 (1.大阪大学、2.東京大学地震研究所、3.東京大学大学院情報理工学系研究科、4.防災科学技術研究所)

キーワード:統計地震学、ETASモデル、スコアマッチング

Immediate forecasting of the temporal and spatial distribution of aftershock sequences is vital for disaster prevention. However, identifying the number of aftershocks immediately after the main shock is challenging due to the contaminations of arriving seismic waves. To overcome this difficulty, some researchers introduced detection functions of the aftershocks to correct the bias caused by the underdetection of the aftershocks. However, existing models of the detection probability for an aftershock do not utilize the information on aftershock sequences that occurred before the aftershock, which vitiates model flexibility. We aim to propose a model that can fully employ the local information of the aftershock sequences.

On the other hand, the Omori-Utsu law is well-known for the law of aftershock frequency, and the ETAS (epidemic-type aftershock sequences) model extends the Omori-Utsu law to make the past information available. We propose a simple detection function that can use the past information of the aftershocks like ETAS. However, the estimation of the model is cumbersome because the likelihood includes multiple integrals that are unrealistic to compute. Therefore, we avoid using the maximum likelihood estimation and propose an effective method without computing the multiple integrals using the score-matching technique. The proposed method is applied to the 2004 Chuetsu Earthquake and the 2016 Kumamoto Earthquake.