Earthquake swarms in Taiwan: A composite declustering method for detection and their spatial characteristics

Wei Peng, David Marsan, Kate Huihsuan Chen*, Erwan Pathier

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

摘要

Earthquake swarms can act as indicators of fluid activity and aseismic transients at depth. As a young and active collisional mountain belt with frequent earthquakes, Taiwan is a natural laboratory for studying the physical mechanisms controlling the characteristics of swarm activity in this complex tectonic environment. Where the earthquake swarms tend to occur and how they reflect the aseismic deformation in this young orogen? In this study, we propose a composite swarm detection method that relies on the correlation of mainshock density rates derived from three distinct declustering algorithms. Using earthquakes in Taiwan from 1990–2019 with magnitudes greater than or equal to three and at depths less than 50 km, 153 swarm sequences were identified as characterized by an event number greater than ten, a time span of less than fifteen days, and a maximum magnitude of 5.79. The swarm sequences were found to be active at locations with a high seismicity rate (>0.2yr−1km−2) but not an anomalous b-value, suggesting that the environment with a high rate of earthquake occurrence is linked with the mechanism for swarm generation. They were found to largely overlap with the repeating earthquakes, as approximately 86% of the 1857 repeating events in Taiwan are closely located to swarm events. Such overlap is found to be largest in the southern Longitudinal Valley where a creeping fault is located and where a low coupling ratio was inferred. Consequently, it is proposed that the active collision boundary experiencing a high creep rate and the areas experiencing episodic aseismic slip are capable of producing active swarm sequences in Taiwan.

原文英語
文章編號117160
期刊Earth and Planetary Science Letters
574
DOIs
出版狀態已發佈 - 2021 十一月 15

ASJC Scopus subject areas

  • 地球物理
  • 地球化學與岩石學
  • 地球與行星科學(雜項)
  • 空間與行星科學

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