Micro-seismicity in the Seoul Metropolitan Area, Korea

Abstract

A minor earthquake with magnitude 3.0 occurred in the Seoul Metropolitan Capital Area (SNCA), Korea, on 9 February 2010. The earthquake attracted much attention from media, politicians, policy makers and the public, who raised concerns about seismic hazards and risks in the Korea Peninsula, in particular, to the SNCA. SNCA includes the Seoul and Incheon metropolitans and most of the Gyeonggi province. It has a population of 24.5 million (as of 2007) and is ranked as the second largest metropolitan area in the world. The SNCA has been the center of the economics, politics, and culture during the past half millennium since the city has been designated as the capital city in 1394. We applied waveform correlation detector to 2007-2010 continuously recorded seismic data to identify repeating earthquakes. We identify 9 micro-earthquakes during 2007-2010 periods which are not reported in the KNSN bulletin because their magnitudes are too small. Estimated magnitudes using amplitude ratios measured at the station SEO indicate the smallest event detected by the waveform cross correlation technique in the study is as low as 0.19. The number of events for our interpretation becomes 11 including two previously reported events and nine newly identified micro-earthquakes. All of them occur in a very small area. While there are historic documents reporting earthquakes in the SNCA, repeating earthquakes orabout seismic hazards and risks in the Korea Peninsula, in particular, to the SNCA. SNCA includes the Seoul and Incheon metropolitans and most of the Gyeonggi province. It has a population of 24.5 million (as of 2007) and is ranked as the second largest metropolitan area in the world. The SNCA has been the center of the economics, politics, and culture during the past half millennium since the city has been designated as the capital city in 1394. We applied waveform correlation detector to 2007-2010 continuously recorded seismic data to ident