FastFind »   Lastname: doi:10.1029/ Year: | Advanced Search  

AGU: Geophysical Research Letters

 

Keywords

  • fluid pressure
  • slow earthquakes
  • tomography and receiver function

Index Terms

  • Seismology: Subduction zones
  • Seismology: Seismicity and tectonics
  • Seismology: Tomography
  • Structural Geology: Role of fluids
  • Tectonophysics: Dynamics and mechanics of faulting

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 37, L14310, 5 PP., 2010
doi:10.1029/2010GL043723

Variations of fluid pressure within the subducting oceanic crust and slow earthquakes

Aitaro Kato

Earthquake Research Institute, University of Tokyo, Tokyo, Japan

Takashi Iidaka

Earthquake Research Institute, University of Tokyo, Tokyo, Japan

Ryoya Ikuta

Department of Geosciences, Shizuoka University, Shizuoka, Japan

Yasuhiro Yoshida

Meteorological Research Institute, Tsukuba, Japan

Kei Katsumata

Institute of Seismology and Volcanology, Hokkaido University, Sapporo, Japan

Takaya Iwasaki

Earthquake Research Institute, University of Tokyo, Tokyo, Japan

Shin'ichi Sakai

Earthquake Research Institute, University of Tokyo, Tokyo, Japan

Clifford Thurber

Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, USA

Noriko Tsumura

Graduate School of Science, Chiba University, Chiba, Japan

Koshun Yamaoka

Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan

Toshiki Watanabe

Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan

Takahiro Kunitomo

Department of Geosciences, Shizuoka University, Shizuoka, Japan

Fumihito Yamazaki

Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan

Makoto Okubo

Tono Research Institute of Earthquake Science, Association for the Development of Earthquake Prediction, Mizunami, Japan

Sadaomi Suzuki

Tono Research Institute of Earthquake Science, Association for the Development of Earthquake Prediction, Mizunami, Japan

Naoshi Hirata

Earthquake Research Institute, University of Tokyo, Tokyo, Japan

We show fine-scale variations of seismic velocities and converted teleseismic waves that reveal the presence of zones of high-pressure fluids released by progressive metamorphic dehydration reactions in the subducting Philippine Sea plate in Tokai district, Japan. These zones have a strong correlation with the distribution of slow earthquakes, including long-term slow slip (LTSS) and low-frequency earthquakes (LFEs). Overpressured fluids in the LTSS region appear to be trapped within the oceanic crust by an impermeable cap rock in the fore-arc, and impede intraslab earthquakes therein. In contrast, fluid pressures are reduced in the LFE zone, which is deeper than the centroid of the LTSS, because there fluids are able to infiltrate into the narrow corner of the mantle wedge, leading to mantle serpentinization. The combination of fluids released from the subducting oceanic crust with heterogeneous fluid transport properties in the hanging wall generates variations of fluid pressures along the downgoing plate boundary, which in turn control the occurrence of slow earthquakes.

Received 24 April 2010; accepted 1 June 2010; published 29 July 2010.

Citation: Kato, A., et al. (2010), Variations of fluid pressure within the subducting oceanic crust and slow earthquakes, Geophys. Res. Lett., 37, L14310, doi:10.1029/2010GL043723.

Cited By

Please wait one moment ...