11:00 AM - 11:15 AM
[SGD01-08] Complex Faulting in Eastern Taiwan: Insights from GNSS and InSAR observations during the 2024 Mw 7.4 Hualien Earthquake
Keywords:Crustal deformation, GNSS, InSAR, Modelling, Taiwan
Taiwan, located at the complex convergent boundary between the Philippine Sea and Eurasian plates, is one of the most seismically active regions in the world. The interaction of multiple fault systems in eastern Taiwan generates frequent large earthquakes, making precise geodetic monitoring essential for understanding crustal deformation and seismic hazards.
On April 2, 2024, an Mw 7.4 earthquake struck the northern Longitudinal Valley in eastern Taiwan, approximately 18 km south-southwest of Hualien, causing significant structural damage, ground deformation, and casualties. Given the region’s intricate tectonic framework, characterizing the rupture process of this event is crucial for improving fault models and assessing seismic risk.
In this study, we utilize high-resolution geodetic data, including Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) measurements, to analyze coseismic deformation and fault slip distribution. GNSS displacement vectors and InSAR-derived surface deformation patterns provide key constraints on the fault rupture geometry.
We test various fault configurations, including single-fault models with a high-angle east-dipping Longitudinal Valley Fault (LVF) and a shallow west-dipping Central Range Fault (CRF). While these models explain portions of the observed displacement field, they do not fully account for the seismotectonic complexity of the large crustal volume affected by the 2024 Mw 7.4 Hualien seismic sequence. To address this, we developed a composite fault scenario based on aftershock distribution and the complex fault arrangement proposed for the northernmost Longitudinal Valley region.
Our results indicate that a composite fault model best explains the geodetic observations. The inferred rupture involved multiple fault segments, including a major west-dipping fault associated with the CRF, a deeper segment of the east-dipping LVF, and slip along the Milun Fault. This complex rupture pattern aligns well with aftershock distribution and the known structural architecture of the region.
This study highlights the importance of considering multi-segment ruptures in seismic hazard assessments, as earthquakes in eastern Taiwan often involve complex fault interactions rather than isolated single-fault ruptures. Due to this seismotectonic complexity, the seismic hazard in the region will likely remain high, particularly at the southern and northern ends of the 2024 seismic sequence, where Coulomb stress typically increases.
These findings underscore the critical role of geodetic techniques in refining our understanding of fault systems and earthquake mechanics. The integration of GNSS and InSAR data enables a more detailed and accurate reconstruction of coseismic deformation, improving regional seismic hazard models. Given Taiwan’s vulnerability to large earthquakes, advancing geodetic methodologies is essential for enhancing disaster preparedness and mitigation strategies.
This research contributes to ongoing efforts to develop dynamic reference frameworks for monitoring crustal deformation and provides valuable insights into the interplay between tectonic forces and seismic activity in this highly active region.
On April 2, 2024, an Mw 7.4 earthquake struck the northern Longitudinal Valley in eastern Taiwan, approximately 18 km south-southwest of Hualien, causing significant structural damage, ground deformation, and casualties. Given the region’s intricate tectonic framework, characterizing the rupture process of this event is crucial for improving fault models and assessing seismic risk.
In this study, we utilize high-resolution geodetic data, including Global Navigation Satellite System (GNSS) and Interferometric Synthetic Aperture Radar (InSAR) measurements, to analyze coseismic deformation and fault slip distribution. GNSS displacement vectors and InSAR-derived surface deformation patterns provide key constraints on the fault rupture geometry.
We test various fault configurations, including single-fault models with a high-angle east-dipping Longitudinal Valley Fault (LVF) and a shallow west-dipping Central Range Fault (CRF). While these models explain portions of the observed displacement field, they do not fully account for the seismotectonic complexity of the large crustal volume affected by the 2024 Mw 7.4 Hualien seismic sequence. To address this, we developed a composite fault scenario based on aftershock distribution and the complex fault arrangement proposed for the northernmost Longitudinal Valley region.
Our results indicate that a composite fault model best explains the geodetic observations. The inferred rupture involved multiple fault segments, including a major west-dipping fault associated with the CRF, a deeper segment of the east-dipping LVF, and slip along the Milun Fault. This complex rupture pattern aligns well with aftershock distribution and the known structural architecture of the region.
This study highlights the importance of considering multi-segment ruptures in seismic hazard assessments, as earthquakes in eastern Taiwan often involve complex fault interactions rather than isolated single-fault ruptures. Due to this seismotectonic complexity, the seismic hazard in the region will likely remain high, particularly at the southern and northern ends of the 2024 seismic sequence, where Coulomb stress typically increases.
These findings underscore the critical role of geodetic techniques in refining our understanding of fault systems and earthquake mechanics. The integration of GNSS and InSAR data enables a more detailed and accurate reconstruction of coseismic deformation, improving regional seismic hazard models. Given Taiwan’s vulnerability to large earthquakes, advancing geodetic methodologies is essential for enhancing disaster preparedness and mitigation strategies.
This research contributes to ongoing efforts to develop dynamic reference frameworks for monitoring crustal deformation and provides valuable insights into the interplay between tectonic forces and seismic activity in this highly active region.