Seismic reflection profiling across the source fault of the 2003 Northern Miyagi earthquake (Mj 6.4), NE Japan: Basin inversion of Miocene back-arc rift

Naoko Kato, Hiroshi Sato, Toshifumi Imaizumi, Yasutaka Ikeda, Shinsuke Okada, Kyoko Kagohara, Taku Kawanaka, Keiji Kasahara

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The Northern Miyagi earthquake (Mj 6.4) on 26 July, 2003, was a shallow crustal earthquake produced by high-angle reverse faulting. To construct a realistic geologic model for this fault system from depth to the surface, seismic reflection profiling was carried out across the northern part of the source fault of this earthquake. The common mid-point seismic reflection data were acquired using a vibrator truck along a 12 km-long seismic line. The obtained seismic profile portrays a Miocene half-graben bounded by a west-dipping fault. Consistent with gravity anomaly data, the maximum thickness of the basin fill probably reaches 3 km. From the regional geology, this basin-bounding normal fault forms the eastern edge of the northern Honshu rift system and was produced by rapid extension during 17-15 Ma. The deeper extension of the fault revealed by seismic profiling coincides with the planar distribution of aftershocks. The hypocentral distribution of the aftershocks shows a concentration on a plane dipping 55 degrees to the west with listric geometry. Thus, the basin inversion has been performed using the same fault; the 2003 Northern Miyagi earthquake was generated by fault reactivation of a Miocene normal fault.

Original languageEnglish
Pages (from-to)1369-1374
Number of pages6
Journalearth, planets and space
Volume56
Issue number12
DOIs
Publication statusPublished - 2004

Keywords

  • 2003 Northern Miyagi earthquake
  • Basin inversion
  • Fault reactivation
  • Miocene back-arc rift
  • NE Japan
  • Seismic reflection profiling

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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