Study of geological structure in area of Hwasan caldera using geophysical method

지구물리학적 방법에 의한 화산 칼데라 지역의 지질구조 연구

  • 권병두 (서울대학교 지구과학교육과) ;
  • 이희순 (경인교육대학교 과학교육과) ;
  • 양준모 (한국해양연구원 해양환경연구본부) ;
  • 박계순 (서울대학교 지구과학교육과) ;
  • 엄주영 (서울대학교 지구과학교육과) ;
  • 김동오 (서울대학교 지구과학교육과)
  • Published : 2007.06.07

Abstract

Uiseong subbasin belonging to Kyungsang basin resulted from volcanic activity in the late Cretaceous. In this study, we carry out MT and gravity survey at the Hwasan caldera, which was formed of volcanic and abyssal rocks complex, then analyze and identify geological substructure. Potential survey such as gravity and magnetic survey has been mainly carried out in former studies, so depth information for understanding substructure was not enough. To complement a potential survey, we use MT method, which has high vertical resolution. Moreover we make a simple 2D model comparing with former study. The result of MT and gravity 2D modeling shows that this area is roughly composed of 3 layers; The bottom layer is a basement. In the second layer, intrusive rocks having high resistivity is placed along the ring faults and the sedimentary layer of low resistivity is inside caldera. The highest layer is alluvium. To comprehend the 3D structure of the Hwasan caldera, we perform 3D gravity inversion, and construct the 3D model from the result of 3D gravity inversion. MT responses are calculated by using the constructed 3D model and the 3D model of the Hwasan caldera's structure is suggested after comparing the calculated values with the observed values at MT line.