講演情報
[P25-03]Dynamic Modeling of Accelerating Foreshocks and Rupture Processes in the 2025 Mw8.8 Kamchatka Earthquake
*渡邊 大起1、金子 善宏1、Kearse Jesse1 (1. 京都大学)
On July 29, 2025, at 23:24 UTC, a magnitude 8.8 earthquake (USGS) struck off the coast of the Kamchatka Peninsula, Russia, generating a tsunami that prompted widespread warnings along the Pacific coast of Japan. The Kamchatka region has historically experienced repeated great earthquakes, including the magnitude 9.0 event of November 4, 1952. According to the USGS catalog, notable foreshock activity preceding the 2025 mainshock began about one month earlier, with the largest foreshock reaching magnitude 7.4 on July 20, approximately 10 days before the mainshock. To investigate the physical mechanisms underlying both the recurrence of such large earthquakes and the development of accelerating foreshocks, we conducted numerical simulations using a fully dynamic earthquake cycle model. The model incorporates heterogeneous frictional properties on a one-dimensional fault, following the framework of Ito & Kaneko (2023). Our simulations successfully reproduce the mainshock magnitude, recurrence interval, and accelerating foreshock activity, suggesting that frictional heterogeneity plays a key role in driving foreshock acceleration prior to the mainshock. In this presentation, we will present the modeling results and discuss their implications through comparisons with the inferred characteristics of the mainshock and its foreshocks.