Hypocenter relocation of microearthquakes in offshore area of northeastern South Korea

Abstract:

Microearthquakes in offshore Gangneung-Sokcho-Goseong area of northeastern South Korea are reviewed and the hypocenters of these events are relocated by double-difference algorithm. Small repeating events occur predominantly in offshore area, whereas onshore events are relatively few and unevenly distributed. Korea Institute of Geoscience and Mineral Resources (KIGAM) catalog lists 566 events for the period Jan 2010 – Jun 2014 with the magnitude range of M_L up to 3.3. The offshore events could be grouped into a number of small clusters that seem to extend ENE – WSW direction. It appears to have little relationship between the location of event clusters and the direction of main onshore faults running NNE – SSW, but it can be correlated with locally developed minor faults in E-W direction. KIGAM deploys additional 5 short period Guralp CMG-40T seismometers along coastline to reinforce event detection capability and improve accuracy of event relocation. Integrated network of permanent and temporary land seismometers and offshore underwater observatory expected to be installed by 2015 would surely bring us much knowledge of the process and the properties of offshore seismic activity.