Open Access

Crustal deformations in Kii peninsula associated with the SE off the Kii peninsula earthquake sequence of September 5, 2004 derived from dense GPS observations

  • Manabu Hashimoto16Email author,
  • Kensuke Onoue16,
  • Fumio Ohya16,
  • Yoshinobu Hoso16,
  • Kohei Segawa16,
  • Kazutoshi Sato16 and
  • Yasuyoshi Fujita16
Earth, Planets and Space201457:BF03351813

https://doi.org/10.1186/BF03351813

Received: 30 November 2004

Accepted: 5 March 2005

Published: 20 June 2014

Abstract

We present crustal deformations in southern Kii peninsula, southwest Japan, before and after the SE off the Kii peninsula earthquake sequence of September 5, 2004, which were obtained from repeated surveys of dense GPS network. Disaster Prevention Research Institute (hereafter DPRI), Kyoto University made a reoccupation of their dense GPS network network that was occupied in February-March, 2004, right after the event to obtain crustal deformations associated with this event. Since we do not have the data just before the event, we apply an inversion of displacements of GEONET sites during the period from February-March to August, and interpolate displacements at DPRI’s sites using the inverted fault model. Southward movements of about 2 cm are obtained in the middle of Kii peninsula, while displacements are rotated to southwest on the west side. These characteristics of horizontal displacement field cannot be explained only by a pure thrust faulting, but additional sources such as right-lateral faulting on a NW-SE trending fault are required.

SE off the Kii peninsula earthquakes GPS crustal deformation fault model