Open Access

Coseismic and postseismic deformation related to the 2007 Chuetsu-oki, Niigata Earthquake

  • Yusaku Ohta15Email author,
  • Satoshi Miura15,
  • Takeshi Iinuma15,
  • Kenji Tachibana15,
  • Takeshi Matsushima25,
  • Hiroaki Takahashi35,
  • Takeshi Sagiya45,
  • Takeo Ito45,
  • Shin’ichi Miyazaki55,
  • Ryosuke Doke65,
  • Akira Takeuchi65,
  • Kayo Miyao15,
  • Akihiko Hirao25,
  • Takahiro Maeda35,
  • Teruhiro Yamaguchi35,
  • Masamitsu Takada35,
  • Makiko Iwakuni55,
  • Tadafumi Ochi55,
  • Irwan Meilano45 and
  • Akira Hasegawa15
Earth, Planets and Space200860:BF03353140

https://doi.org/10.1186/BF03353140

Received: 4 December 2007

Accepted: 28 April 2008

Published: 18 November 2008

Abstract

An intermediate-strength earthquake of magnitude Mj 6.8 occurred on July 16, 2007, centered beneath the Japan Sea a few kilometers offshore of Niigata Prefecture in central Japan. We constructed a dense GPS network to investigate postseismic deformation after this event, choosing our GPS sites carefully so as to complement the nationwide GPS GEONET array. Coseismic displacements caused by the mainshock detected at some GEONET sites were used to estimate coseismic fault parameters. The results indicate that the geodetic data can be explained by a combination of two rectangular faults dipping northwest and southeast. Minor but definite postseismic deformation was detected largely in the southern part of the dense network. The time series of site coordinates can be characterized by a logarithmic decay function, and the estimated time constant seems to be almost similar in range to that of the 2004 Mid-Niigata Prefecture Earthquake. We also found a possible site instability at 960566 (Izumo-zaki, GEONET) caused by a small, local landslide associated with the mainshock and therefore concluded that the data obtained at this site should not be used for coseismic or postseismic analysis.

Key words

Crustal deformation coseismic slip postseismic deformation GPS Niigata-Kobe Tectonic Zone