Journal Article

Fast report: applying a weighted template-matching algorithm (WTMA) to investigate the seismogenic structures and microseismic activity of the 2025 ML6.4 Dapu earthquake sequence in Taiwan

Lee, En-Jui, Chen, Po, Rau, Ruey-Juin, Wen, Strong, Chen, Da-Yi, Lee, Yuan-Hsi, Liang, Wen-Tzong, Ching, Kuo-En, Liao, Wu-Yu

2025

Overview

This study analyzes seismic activity related to the 2025 ML 6.4 Dapu earthquake sequence in Chiayi County and Tainan City, Taiwan. By integrating a machine learning-based earthquake catalog with the Weighted Template Matching Algorithm (WTMA), over 40,000 microseismic events were detected, many of which were previously undetected due to waveform overlap with other seismic events. These microseismic detections enhance the understanding and interpretation of detailed aftershock distributions. Additionally, Centroid Moment Tensor (CMT) solutions were analyzed for further insights into the underlying seismogenic structures. In particular, the mainshock region exhibits complex structural features characterized by both east-dipping detachment faults and reactivated west-dipping basement faults occurring at varying depths. These findings highlight the intricate structural dynamics within Taiwan's actively deforming orogenic belt. The results also suggest that interactions within the fault system triggered progressive seismic activity, gradually propagating to adjacent areas. Such insights are critical for refining seismic hazard assessments and contribute to enhanced understanding of regional tectonic processes. Key points WTMA provides a more complete earthquake catalog, refining the spatial distribution of seismicity. The Dapu earthquake sequence reveals both east-dipping faults and reactivated west-dipping basement faults contributing to seismic activity. The delayed activation of seismicity in adjacent regions suggests complex post-seismic fault interactions.

• Publisher: Springer Nature Singapore,Springer Nature B.V,Springer
• Subject: 2025 Dapu earthquake / Accuracy / Aftershocks / Algorithms / Atmospheric Sciences / Basements / Catalogues / Centroids / Dipping / Earth and Environmental Science / Earth Sciences / Earthquakes / Fault lines / Faults / Fold-and-thrust belt / Geological hazards / Hazard assessment / Machine learning / Microseismic detection / Microseisms / Oceanography / Orogeny / Refining / Seismic activity / Seismic hazard / Seismicity / Seismogenic structures / Signal to noise ratio / Spatial distribution / Structural dynamics / Tectonic processes / Tectonics / Template matching / Tensors / Velocity / Waveforms / Weighted template-matching