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Unveiling Shallow Earthquake Ruptures in the Ryukyu Area: A Comprehensive Study Through Bp Imaging and Regional Cmt Catalog

Description: 

In the last few centuries, the absence of significant interplate or tsunamigenic earthquakes has led to ambiguous conclusions regarding the coupling rate in the Ryukyu subduction zone. Estimations of large slip-deficit rates from GPS data and the discovery of slow earthquakes suggest both strong and weak coupling rates. Despite these geophysical observations, the seismic database for small to large earthquakes remains incomplete due to the limited coverage of seismic networks. Discrepancies in focal depths between the JMA event catalog, GCMT, and NIED CMT solutions further challenge understanding seismogenic structures. To address this, our study aims to enhance the CMT catalog covering small to large earthquakes (M≥4) from 2000 to 2022. We include three broadband networks to ensure better azimuth coverage: BATS (Broadband Array in Taiwan for Seismology), F-net from NIED, and FJ-network (Fujian Earthquake Agency). The AutoBATS MT algorithm is adapted to facilitate the necessary epicenter scanning for CMT inversion. For the western Ryukyu area, our inversion results for larger earthquakes are overall consistent with the GCMT solutions. For earthquakes larger than 6.0, we also apply Multiple signal classification (MUSIC) back-projection imaging to determine the causative fault planes, rupture extends, and durations. The rupture properties of major earthquakes and the comprehensive regional CMT catalog may offer additional insights into future studies on coupling rates.

Session: Characteristics and Mechanics of Fault Zone Rupture Processes, from Micro to Macro Scales [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Pei-Ru

Student Presenter: No

Invited Presentation: 

Authors