[S-CG45] Science of slow-to-fast earthquakes

[SCG45-16] Triggered Slow Slip Event on an Inland Fault in the Hengchun Peninsula, Taiwan: Insights from Geodetic Data and Earthquake Sequence Simulation

*蕭 詩涵¹、景 國恩¹、安藤 亮輔²、Slawomir Jack Giletycz³、張 午龍³、陳 建良⁴ (1.國立成功大學、2.東京大學、3.國立中央大學、4.經濟部地質調查及礦業管理中心)

キーワード：慢地震、恆春斷層、地震循環模擬、地震潛勢

Our previous study proposed an ongoing triggered slow slip event (SSE) on the inland Hengchun fault (HCNF) following the 2006 M_L 7.0 Pingtung offshore earthquake in Taiwan. This SSE was identified based on 3 precise leveling routes, 13 continuous GNSS stations, 37 campaign-mode GNSS stations, and a kinematic model covering the Hengchun Peninsula from 2002 to 2022. The surface velocity fields not only indicate that the trace of the HCNF should be shifted 1–2 km eastward but also reveal a time-varying velocity pattern that can be classified into five periods: (1) the interseismic period from 2002 to the 2006 Pingtung offshore earthquake; (2) the 2^nd period after the earthquake to April 2010; (3) the 3^rd period from April 2010 to 2013; (4) the 4^th period from 2013 till 2016; (5) the 5^th period from 2016 till 2022. The slip deficit rate distribution indicates that energy has accumulated along the entire HCNF, primarily in the northern shallow region. The slip rate is also predominantly distributed across the entire fault, with a migration from south to north. However, strain in part of the main accumulation area still remains. In period 5, the velocity pattern and slip area have begun to return to a pattern similar to period 2. To further investigate this SSE, we conduct a quasi-dynamic model that incorporates a simplified fault trace from our previous work, fault geometry from the Taiwan Earthquake Model, and initial stress conditions estimated after the 2006 earthquake to simulate the earthquake sequence on the HCNF.