Fast report: seismogenic structure of the 2025 M6.4 dapu earthquake sequence in western Taiwan revealed by a deep-learning-empowered earthquake catalog

Abstract This study investigates the three-dimensional seismogenic structures associated with the 2025 M6.4 Dapu earthquake in western Taiwan and compares these results with the relocated instrumental earthquake catalog. Utilizing a deep-learning-empowered earthquake cataloging method, 6,805 seismic events were identified from January 20 to 31, 2025, achieving a completeness magnitude ( $$M_{c}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>M</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> ) of 0.4. Notably, the M6.4 earthquake sequence involved the reactivation of a potentially existing fault system, characterized by an east-dipping plane at $$27^\circ$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>27</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> between 5 and 10 km in depth and a west-dipping plane at $$37^\circ$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mn>37</mml:mn> <mml:mo>∘</mml:mo> </mml:msup> </mml:math> between 10 and 15 km depth. The distribution of aftershocks and triggered seismicity reveals a complex pattern of strain accumulation that influences nearby active faults. These findings underscore the necessity of continuous and detailed monitoring to better understand and potentially mitigate future seismic hazards in this region.