Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
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Location of Recent Micro-earthquakes in the Gyeongju Area

최근 경주지역 미소지진 진원 위치

  • Han, Minhui (Deptartment of Geological Sciences, Pusan National University) ;
  • Kim, Kwang-Hee (Deptartment of Geological Sciences, Pusan National University) ;
  • Son, Moon (Deptartment of Geological Sciences, Pusan National University) ;
  • Kang, Su Young (Deptartment of Geological Sciences, Pusan National University) ;
  • Park, Jung-Ho (Earthquake Research Center, Korea Institute of Geosciences and Mineral Resources)
  • 한민희 (부산대학교 지질환경과학과) ;
  • 김광희 (부산대학교 지질환경과학과) ;
  • 손문 (부산대학교 지질환경과학과) ;
  • 강수영 (부산대학교 지질환경과학과) ;
  • 박정호 (한국지질자원연구원 지진연구센터)
  • Received : 2016.03.21
  • Accepted : 2016.04.11
  • Published : 2016.05.31
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Abstract

Small to large earthquakes have been reported in Gyeongju and its vicinity in southeast Korea during historical period as well as instrumental observation period. We identified and located more than 300 earthquakes that occurred between January 2010 and December 2014 in a $20km{\times}30km$ area, but were unreported because of their small magnitudes. We used the Joint Hypocenter Determination (JHD) method to minimize the influence of the differences between the actual earth structure and 1-D velocity model for earthquake locations. The potential relationship between the previously reported Quaternary faults and the earthquake hypocenters was investigated. Many micro-earthquakes were found to be located in the southern segment of the Yeonil Tectonic Line, the Seokup fault, and the Waup basin boundary faults.

우리나라 남동부에 위치한 경주와 그 주변지역에서는 과거부터 최근까지 크고 작은 지진이 반복적으로 발생하고 있다. 계기지진자료를 검토하여 경주 주변 약 $20km{\times}30km$ 지역 내에서 지진이 많이 발생하고 있음을 확인하였다. 본 연구에서는 이 지역에서 2010년 1월부터 2014년 12월 사이에 발생했지만, 그 규모가 너무 작아 미처 보고되지 않은 300개 이상의 미소지진을 식별하고 그 발생위치를 결정하였다. 연구지역 지하의 속도구조와 진원요소 결정에 사용하는 속도모델의 차이로 인한 오차를 줄이기 위하여 JHD 방법을 사용하였다. 연구지역에서는 활성으로 의심되는 제4기 단층들이 여러 장소에서 보고되고 있으므로, 이 단층들과 미소지진발생과의 관련 가능성을 조사하였다. 본 연구에서 새로이 발생사실이 보고되는 미소 지진들은 연일구조선의 남측분절, 석읍단층 그리고 와읍분지 경계단층과 관련이 있는 것으로 나타난다.

Keywords

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