Abstract Subduction zone earthquakes typically occur along plate interfaces or within subducting slabs, but rupture mechanisms at mixed collision–subduction boundaries remain poorly understood. The 2024 Mw 7.4 Hualien earthquake struck the suture between the Philippine Sea Plate and the Eurasian Plate in eastern Taiwan. Joint source inversion reveals that the rupture involved two distinct faults: a west‐dipping subduction interface and a steep tear fault within the slab. The rupture initiated on the intraplate tear fault and propagated onto the interface, producing significant thrust motion. Although uncertainties remain in the detailed fault geometry and limited geodetic constraints, seismological observations consistently support a dual‐faulting process. This event provides direct evidence of slab‐edge detachment coupled with interface slip—a mechanism not previously documented in this region. Our results highlight the structural complexity of this transitional plate boundary and underscore the need to account for such multi‐fault ruptures in regional seismic hazard assessments.
Observations from the Little Bunker
Last updated: November 30, 2025 04:25 AM
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