17:15 〜 19:15
[SCG52-P07] Classification of the April 3rd, 2024 Mw 7.4 Hualien, Taiwan, Aftershock Sequence Using Waveform Cross-Correlation
キーワード：2024 Hualien earthquake, Aftershock classification, Cross-correlation, Fault geometry, Faulting complexity, Offshore seismogenic structure
A destructive Mw 7.4 earthquake struck Hualien, Taiwan, on April 3, 2024, followed by hundreds of felt aftershocks. Understanding the fault geometry of this sequence is crucial for comprehending its seismogenic structure and enhancing future preparedness. In addition to the common Centroid Moment Tensor (CMT) solution for the aftershocks, we utilized the cross-correlation of seismic waveforms to classify the characteristics of the aftershocks sequence.
We firstly analyze M >4 aftershocks that occurred within one week after the mainshock (April 3–10, 2024) from Central Weather Administration (CWA) of Taiwan. Waveform data were collected from all 41 stations of the Broadband Array in Taiwan for Seismology (BATS). We define an earthquake pair as two events separated by a distance of less than 3 km. This threshold is chosen not only to ensure proximity of the sources but also to maintain similar Green’s functions, allowing for more reliable cross-correlation analysis. We considered the time window spanning 1 second before to 5 seconds after the estimated P-wave arrival, applying a 1–8 Hz bandpass filter. For event classification, we compute cross-correlation coefficients for each earthquake pair using waveforms recorded across all channels of the BATS stations. This analysis aims to categorize aftershocks based on their waveform similarities, providing insight into their characteristics, and helping to map the major seismogenic structures through their spatial distribution.
By examing aftershocks patterns and the seismogenic structures in which they occurred, we seek to gain a deeper understanding of the faulting processes involved in the 2024 Hualien earthquake sequence. Additionally, this study explores the possible complexity of the offshore seismogenic structure associated with Ryukyu subduction zone.
We firstly analyze M >4 aftershocks that occurred within one week after the mainshock (April 3–10, 2024) from Central Weather Administration (CWA) of Taiwan. Waveform data were collected from all 41 stations of the Broadband Array in Taiwan for Seismology (BATS). We define an earthquake pair as two events separated by a distance of less than 3 km. This threshold is chosen not only to ensure proximity of the sources but also to maintain similar Green’s functions, allowing for more reliable cross-correlation analysis. We considered the time window spanning 1 second before to 5 seconds after the estimated P-wave arrival, applying a 1–8 Hz bandpass filter. For event classification, we compute cross-correlation coefficients for each earthquake pair using waveforms recorded across all channels of the BATS stations. This analysis aims to categorize aftershocks based on their waveform similarities, providing insight into their characteristics, and helping to map the major seismogenic structures through their spatial distribution.
By examing aftershocks patterns and the seismogenic structures in which they occurred, we seek to gain a deeper understanding of the faulting processes involved in the 2024 Hualien earthquake sequence. Additionally, this study explores the possible complexity of the offshore seismogenic structure associated with Ryukyu subduction zone.