Regional Earthquake Relocation Using Multiple Seismic Arrays: Case Examples From Offshore Eastern Taiwan and Yellow Sea Between China and South Korea

Date: 4/26/2019

Time: 11:15 AM

Room: Elliott Bay

Regional earthquake locations using local seismic network are always subjecting to large uncertainties due to poor spatial coverage of seismic stations, discrepancies on velocity models, and limitations on traditional location technologies. For instance, it is not uncommon that the same earthquake within Yellow Sea may be reported more than tens to hundreds of km apart independently in Chinese and Korean catalogs while there is no mechanism for earthquake data exchange between two countries. Integrating seismic stations into multiple arrays, apparent azimuths and apparent velocities of incoming seismic waves (mainly Pn) from a regional earthquake to each array can be reliably determined. Epicenter of a regional earthquake can thus be reasonably located by tracing seismic rays following the back azimuths derived from multiple arrays. This method has been applied to relocate earthquakes in offshore region of eastern Taiwan using CWB island-wide network data and in Yellow Sea region using KMA network data. In the Taiwan case, relocated epicenters are consistent with that reported by JMA and NEIC. While the apparent velocity ~6.8 km/sec is found for all arrays that implies the propagation of oceanic Pn waves across the ocean-continent transition region into land stations along a path of minimum travel time. In the Yellow Sea case, the apparent velocity ~8.0 km/sec for all arrays suggests a typical continental Pn waves propagating across the continent-continent transition region into Korean Peninsula. The significance of relocated epicenters in the Yellow Sea region is yet to be explored.

Presenting Author: Jer-Ming Chiu

Authors