Earthquake Interactions in Eastern Taiwan: Insight from the 2024 Mw 7.3 Hualien Earthquake

Abstract Since 2000, eastern Taiwan has experienced 38 Mw≥5.5 earthquakes, leaving three seismic gaps along the Longitudinal Valley fault (LVF). In April 2024, the Mw 7.3 Hualien earthquake occurred near the LVF. Herein, we first apply comprehensive geodetic data including Interferometric Synthetic Aperture Radar and Global Navigation Satellite System to estimate two potential fault geometries and invert for the coseismic slip. Our results suggest that a transpressive WNW-dipping low-angle fault related to the Central range fault is responsible for the Mw 7.3 Hualien earthquake. We then perform the Coulomb stress analysis to probe earthquake interaction in eastern Taiwan. The increased stress of ∼2.6 bars due to the preceding major earthquakes at the hypocenter of the 2024 event significantly pushes this fault toward failure. Moreover, the conjugate LVF and the Milun fault are activated, and some aftershocks are promoted here. Finally, we note that the Coulomb stress changes from historical earthquakes and the 2024 Hualien earthquake exert positive stress on the seismic gaps in the northern LVF, potentially influencing future ruptures.