Open Access

Crustal deformation and a preliminary fault model of the 2007 Chuetsu-oki earthquake observed by GPS, InSAR, and leveling

  • Takuya Nishimura17Email author,
  • Mikio Tobita17,
  • Hiroshi Yarai17,
  • Shinzaburo Ozawa17,
  • Makoto Murakami17, 27,
  • Toru Yutsudo17,
  • Masayoshi Ishimoto17,
  • Takeshi Umesawa17,
  • Takashi Toyofuku17,
  • Satoshi Kawamoto17,
  • Tomomi Amagai17,
  • Midori Fujiwara17,
  • Akira Suzuki17,
  • Syunji Enya17,
  • Toshiyuki Sasaki17,
  • Masanori Yokokawa17,
  • Syuichi Oomori17,
  • Setsuo Tanoue17,
  • Hisao Ikeda17,
  • Moriyuki Nemoto17,
  • Hisashi Suito17,
  • Fumi Hayashi17,
  • Hiroshi Une17, 37,
  • Mamoru Koarai17 and
  • Masaharu Tsuzawa17
Earth, Planets and Space200860:BF03353142

https://doi.org/10.1186/BF03353142

Received: 30 November 2007

Accepted: 7 June 2008

Published: 18 November 2008

Abstract

The 2007 Chuetsu-oki earthquake occurred just west off the coast of Kashiwazaki in Niigata Prefecture, Central Japan on July 16, 2007. The permanent GPS network (GEONET) clarifies the coseismic displacement as a thrust faulting whose compressional axis lies in the NW-SE direction. Interferometric analysis of synthetic aperture radar (SAR) images acquired by “Daichi” satellite (ALOS) maps a detailed spatial pattern of the displacement toward the satellite for both ascending and descending orbits. Peak-to-peak displacement reaches approximately 400 mm in the descending orbit interferometric (In)SAR data. Repeated precise leveling shows uplift near the northeast part of the aftershock area and subsidence near the southwestern part. We construct a preliminary fault model by inverting the observed deformation. The preferred model consists of two segments of rectangular faults whose moment magnitude is 6.7 in total. From only the used geodetic data on land, it is difficult to determine which plane in two conjugate planes of the focal solution was ruptured. It is important to consider the effect of a heterogeneous medium and variable slip on the faults as well as other geophysical data to determine the fault model with confidence.

Key words

2007 Chuetsu-oki earthquakecrustal deformationGPSInSARleveling