今週のセミナーについてお知らせいたします。

Here is information of the Unagi-seminar(3 October).

************** うなぎセミナーのご案内 (Unagi-seminar) **************

科目：地震学ゼミナールIV（修士・博士）
日時：10月3日（木）14:00～
場所：宇治キャンパス本館E棟2階E-232D
　　　（地震予知研究センター本館セミナー室）

Date and time: 3rd Oct., 14:00 ~
Room: E-232D @ Main building
Map: http://www.uji.kyoto-u.ac.jp/campus/map.html

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[発表者 (Presenter)]
片上智史（KATAKAMI Satoshi）

[題目 (Title)]
浅部スロー地震の応力応答性
Stress condition for triggering of a shallow slow earthquake

[要旨 (Abstract)]
Dynamic triggering of large, detectable slow slip events (SSEs) is rarely observed, even though regional earthquakes often trigger tectonic tremors and very low-frequency earthquakes. In this study, we investigate stress sensitivity of dynamic triggering of shallow SSEs in the Nankai Trough offshore of Kii Peninsula, Japan. We first identify additional shallow SSEs that have not been reported in previous studies and obtain a 15-year long catalogue of SSEs, some of which are triggered by passing seismic waves originating from large regional earthquakes. We then quantify dynamic and static stress perturbations on the plate interface induced by 18 regional candidate earthquakes using numerical simulations of seismic wave propagation. We find that relatively large dynamic stress changes (of the order of 10 kPa and more) and long durations (>tens of seconds) of large stress perturbations are needed to trigger SSEs that have been detected. Regional earthquakes that can induce such large amplitude and duration of dynamic stresses on a plate interface are relatively rare, which might explain the scarcity of dynamic triggering of large, detectable SSEs along the Nankai as well as other subduction zones. In addition, our analysis suggests that intra-slab earthquakes can efficiently trigger SSEs in subduction zones via less-attenuated, slab-guided waves. Furthermore, our results support the idea that an accretionary wedge in subduction zones promotes the dynamic triggering of shallow SSEs.

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