Audio-frequency magnetotelluric imaging of the Hijima fault, Yamasaki fault system, southwest Japan

作者：Yamaguchi Satoru^*; Ogawa Yasuo; Fuji ta Kiyoshi; Ujihara Naoto; Inokuchi Hiroo; Oshiman Naoto

来源：Earth Planets and Space, 2010, 62(4): 401-411.

DOI：10.5047/eps.2009.12.007

• Hijima fault
• Yamasaki fault system
• audio-frequency magnetotelluric
• conductivity structure

An audio-frequency magnetotelluric (AMT) survey was undertaken at ten sites along a transect across the Hijima fault, a major segment of the Yamasaki fault system, Japan. The data were subjected to dimensionality analysis, following which two-dimensional inversions for the TE and TM modes were carried out. This model is characterized by (1) a clear resistivity boundary that coincides with the downward projection of the surface trace of the Hijima fault, (2) a resistive zone (>500 Omega m) that corresponds to Mesozoic sediment, and (3) shallow and deep two highly conductive zones (30-40 Omega m) along the fault. The shallow conductive zone is a common feature of the Yamasaki fault system, whereas the deep conductor is a newly discovered feature at depths of 800-1,800 m to the southwest of the fault. The conductor is truncated by the Hijima fault to the northeast, and its upper boundary is the resistive zone. Both conductors are interpreted to represent a combination of clay minerals and a fluid network within a fault-related fracture zone. In terms of the development of the fluid networks, the fault core of the Hijima fault and the highly resistive zone may play important roles as barriers to fluid flow on the northeast and upper sides of the conductive zones, respectively.

• 出版日期2010
• 单位防灾科技学院