Intesity and phase Indetificaion of the 13 June 1997 Kyeongju Earthquake

1997년 6월 26일 경주지진의 진도 및 파형분석

The intesity survery on the 26 June 1997 Kyeongju Earthquake whose magnitude is 4.3, has been made for 316 locations throughout southen park of Korean Peninsula, then we have investigated the intensities distribution of the earthquake. Because the earthquake was occurred during night time (03:50:23.19), the most people who live farather than about 200km from the epicenter did not feel the earthquake. Therefore, the intensities are estimated only from IV to V in this study. The iso-seismal intensity map shows that the shape of iso-seismal intensity is similar to the boundary of the Kyeongsang Basin. This phenomenon may indicates that the energy of the earthquake is trapped within the Kyeongsang Basin due to low velocity within the basin compared with the velocity outside of the basin. The travel time curves with 10 possible phases are used to identify the earquake records. The Pg and Sg phases are crearly shown in the records whose epicental distance is less than 60 km. The records of MUN and PCH stations located outside of the Kyiongsang Basin show different frequency compared with that of the other stations located within the Kyeongsang Basin.