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Comparative Analysis of the M 7.4 April 3rd, 2024, and ML6.9 Nov. 15th, 1986, Earthquakes in Hualien, Taiwan

Description: 

On April 3rd, 2024, a significant ML7.2 (Mw7.4) earthquake struck offshore Hualien, causing severe ground shaking felt across the entire island, with local intensity reaching 6+ (PGA>400 gal; PGV>0.8m/s). Even Taipei, approximately 100km from the epicenter, experienced severe shaking (PGA> 200 gal), marking Taiwan's largest earthquake since the 1999 Chi-Chi Mw7.6 Earthquake. The Hualien region, situated near the Ryukyu subduction zone, has historically experienced seismic activity. Notably, severe earthquakes occurred in October and November of 1951. Additionally, a similar event on November 15th, 1986, inflicting severe damage on Taipei Metropolitan. The resemblances in shaking patterns between the 1986 and 2024 earthquakes provide valuable insights for understanding the impact of such collision zone earthquakes, especially on nearby cities and distant Taipei Metropolitan. Following the 1986 earthquake, Taiwan initiated the Taiwan Strong Motion Implementation Program (TSMIP) in 1993, highlighting the importance of seismic monitoring and hazard assessment. The preliminary finite-fault model based on seismic, GPS, and InSAR data for the 20240403 earthquake suggests it may have resulted from an offshore western-dipping fault, with a significant slip as an asperity at a depth of around 20-30km inland. In contrast, the fault plane determination for the 1986 earthquake considered an eastern-dipping rupture plane, though data at that time were limited. Resolving this discrepancy in fault plane orientation is crucial for understanding the seismogenic structure from offshore to inland Taiwan. This study aims to compare seismic waveforms, analyze tectonic implications, and enhance future seismic hazard assessment efforts in Hualien and beyond.

Session: The 3 April 2024 Magnitude 7.4 and 6.4 Earthquakes and Aftershock Sequence Near Hualien City, Eastern Taiwan - I

Type: Oral

Date: 5/3/2024

Presentation Time: 10:45 AM (local time)

Presenting Author: Kuo-Fong

Student Presenter: No

Invited Presentation: 

Authors