ミシガン州立大学のFreymuller教授によるAlaska半島の地震系列と沈み込み帯地震サイクルについてのセミナーをハイブリッド形式で開催いたします。興味がおありの方は是非ご参加ください。詳細な情報は以下のとおりです。

日時：2024年 3月 18日 (月) 15:30 -17:00　[Time: March 18, 15:30-17:00]
場所：防災研究所 本館E棟２階E232室　[Place: DPRI, main building, E232]
Title：The 2020-2021 Alaska Peninsula Earthquake Sequence and Megathrust Earthquake Cycle
Speaker：Prof. Dr. Jeffrey T. Freymueller
　　　　　Endowed Chair for Geology of the Solid Earth and Department Chair
　　　　　Dept. of Earth and Environmental Sciences
　　　　　Michigan State University
Abstract：The 2020-2021 Alaska Peninsula earthquake sequence provides a great opportunity to study the megathrust slip budget and earthquake cycle in a region with well-known along-strike changes in the pattern of interseismic slip deficit. The July 2020 M7.8 Simeonof earthquake ruptured across part of the Shumagin Gap, a region with significant interseismic creep, and was followed by the July 2021 M8.2 Chignik earthquake to the NE. In between the enigmatic October 2020 M7.6 Sand Point earthquake occurred within the downgoing plate. In modeling the coseismic and postseismic deformation from these events, we find that the spatial pattern of postseismic deformation contains key new information about the coseismic slip. We use stress-driven afterslip models to infer where the largest coseismic stress changes must have occurred, and these observations require the coseismic slip to terminate relatively abruptly in the downdip direction. The data are better fit by a convex-downward profile of slip as a function of depth, rather than the convex-upward profile that typically results from applying Laplacian smoothing in coseismic slip inversions. The exponential temperature dependence in many rock deformation flow laws also supports a convex-downward profile.