High pore fluid pressure may cause silent slip in the Nankai Trough.

Kodaira, Shuichi; Iidaka, Takashi; Kato, Aitaro; Park, Jin-Oh; Iwasaki, Takaya; Kaneda, Yoshiyuki · Science · 2004

basic_science · Level V

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Abstract

Silent-slip events have been detected at several subduction zones, but the cause of these events is unknown. Using seismic imaging, we detected a cause of the Tokai silent slip, which occurred at a presumed fault zone of a great earthquake. The seismic image that we obtained shows a zone of high pore fluid pressure in the subducted oceanic crust located down-dip of a subducted ridge. We propose that these structures effectively extend a region of conditionally stable slips and consequently generate the silent slip.