The Hualien Earthquake triggered seismic activity in South Korea

The Hualien Earthquake (HEQ) of April 3, 2024, with a magnitude of 7.2 (7.4 by USGS), had significant geophysical impacts not only in Taiwan but also in South Korea, located approximately 1700 km away from the epicenter. Following the HEQ and its large aftershocks (M > 6.0), gravity measurements in South Korea recorded three distinct disturbances, temporally aligned with the mainshock and subsequent seismic events. Simultaneously, micro-seismic activity intensified along the northeast–southwest trending intraplate tectonic boundary between the Okcheon Belt and Yeongnam Massif. These findings suggest a potential case of transient stress triggering , whereby seismic energy from a distant earthquake perturbs the regional stress field and reactivates intraplate fault systems. The sustained increase in seismicity over 40 days following the HEQ highlights the importance of integrating gravity monitoring with seismic observation systems to detect and interpret remote geophysical responses. This study provides new insight into the possibility that the Korean peninsula, typically considered a tectonically stable region, may be vulnerable to dynamic stress effects from distant large-magnitude earthquakes such as the HEQ.