A Study of Lg attenuation around the Korea

The Korean Peninsula experienced heavy shaking by the Fukuoka earthquake on March 20, 2005, and have recognized the potential hazard of large events out of the peninsula. From the viewpoint of seismic hazard, seismic amplitude decrease Q is very important. Related to the crustal cracks induced by the earthquakes, the value of Q (low Q regions are more attenuating than high Q regions) shows a correlation with seismic activity; relatively lower values of Q have been observed in seismically active areas than in stable areas. Korea, example of continental crust, exhibits the prominent Lg wave at regional distances. Recently, we obtained low Q value for Lg waves by two researches (Chung & Lee, 2003; Chung et al., 2005). These results are, however, limited values in the narrow frequency range caused by short inter-station distances of Korea. In addition, we analyzed international seismic array data provided by the Incorporated Research Institutions for Seismology (IRIS): four Chinease stations, two Japanease stations and one Korean stations. From 1997 to 2006, we obtained 346 events and 755 paths for the reversed two-station method (RTSM); these results agree with the values recently reported by Xie et al (2006). We now analyze and will report the Lg attenuation structure of the Yellow Sea based on the combination of China-Korea stations.