Open Access

Deep structure of the Nagamachi-Rifu fault deduced from small aperture seismic array observations

  • Kazutoshi Imanishi1Email author,
  • Hisao Ito1,
  • Yasuto Kuwahara1,
  • Yutaka Mamada1,
  • Takanobu Yokokura1,
  • Naomi Kano1,
  • Kazuo Yamaguchi1 and
  • Akiko Tanaka1
Earth, Planets and Space201454:BF03353297

Received: 28 December 2001

Accepted: 4 June 2002

Published: 26 June 2014


A seismic reflection survey using both explosives and vibrators was conducted in June 2001 around the Nagamachi-Rifu fault, northeastern Japan. We carried out observations of four small aperture seismic arrays in the area to reveal detailed structures of the fault. Array analysis was applied to waveform data from 15 explosives to obtain P-wave scatterer distributions in the area. The obtained P-wave scatterer distribution correlates in space with microearthquake activities and heterogeneous structures such as S-wave reflectors, a structure of caldera, and Mohorovicic discontinuity. We could also image that a sub-horizontal layer with a length of about 10 km exists in the deep extension of the Nagamachi-Rifu fault beneath the seismogenic layer.