Seismic Activity in Hualien, Taiwan: Geological Context and Recent Events

Hualien County lies along Taiwan’s eastern coast, a region shaped by intense tectonic forces. The area sits at the boundary between the Philippine Sea Plate and the Eurasian Plate, where oblique collision produces frequent seismic activity. The Longitudinal Valley, a major suture zone, runs through the county and accommodates significant crustal deformation. This setting results in both shallow crustal earthquakes and deeper events associated with subduction processes. Taiwan experiences hundreds of earthquakes annually due to its position on the Pacific Ring of Fire. Historical records document major events throughout the twentieth century, including destructive quakes in 1951 and 1986 that affected Hualien. The region’s geology features complex fault systems, including the Milun Fault and segments of the Longitudinal Valley Fault, which contribute to ongoing strain accumulation. On 31 March 2002 at 06:52 local time, a magnitude 7.1 earthquake struck 67 km ENE of Hualien City at a depth of 32.8 km. This event occurred within the broader tectonic framework of plate convergence. More recently, on 2 April 2024, a magnitude 7.4 earthquake took place 15 km south of Hualien City. The epicenter of the 2024 event lay approximately 76 km from the 2002 rupture zone, highlighting the persistent activity along nearby fault structures. Both events underscore the region’s elevated seismic hazard. The 2002 earthquake originated at intermediate depth, consistent with the subduction-related seismicity common east of Taiwan. The 2024 mainshock, by contrast, involved shallower faulting that produced stronger ground shaking in populated areas. Aftershock sequences following each quake further illustrate the release of stored tectonic stress. Geological studies indicate that Hualien’s landscape continues to evolve rapidly. Uplift rates in the Central Range exceed several millimeters per year, driven by the same plate motions responsible for the earthquakes. Monitoring networks operated by Taiwan’s Central Weather Administration provide real-time data that improve understanding of fault behavior and support hazard mitigation. Future risk reduction depends on continued investment in building codes, early-warning systems, and public preparedness. The interplay between the Philippine Sea and Eurasian plates ensures that eastern Taiwan will remain one of the world’s most seismically active zones.

References

USGS Earthquake Catalog (events of 31 Mar 2002 and 2 Apr 2024) Central Weather Administration, Taiwan (seismic monitoring reports)