Seismic imaging and velocity structure around the JFAST drill site in the Japan Trench: low V p, high V p-V s in the transparent frontal prismReport as inadecuate




Seismic imaging and velocity structure around the JFAST drill site in the Japan Trench: low V p, high V p-V s in the transparent frontal prism - Download this document for free, or read online. Document in PDF available to download.

Earth, Planets and Space

, 66:121

4. SeismologyNew Perspective of Subduction Zone Earthquake

Abstract

Seismic image and velocity models were obtained from a newly conducted seismic survey around the Integrated Ocean Drilling Program IODP Japan Trench Fast Drilling Project JFAST drill site in the Japan Trench. Pre-stack depth migration PSDM analysis was applied to the multichannel seismic reflection data to produce an accurate depth seismic profile together with a P wave velocity model along a line that crosses the JFAST site location. The seismic profile images the subduction zone at a regional scale. The frontal prism where the drill site is located corresponds to a typically seismically transparent or chaotic zone with several landward-dipping semi-continuous reflections. The boundary between the Cretaceous backstop and the frontal prism is marked by a prominent landward-dipping reflection. The P wave velocity model derived from the PSDM analysis shows low velocity in the frontal prism and velocity reversal across the backstop interface. The PSDM velocity model around the drill site is similar to the P wave velocity model calculated from the ocean bottom seismograph OBS data and agrees with the P wave velocities measured from the core experiments. The average V p-V s in the hanging wall sediments around the drill site, as derived from OBS data, is significantly larger than that obtained from core sample measurements.

KeywordsJapan Trench Seismic image P and S wave velocities JFAST Electronic supplementary materialThe online version of this article doi:10.1186-1880-5981-66-121 contains supplementary material, which is available to authorized users.

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Author: Yasuyuki Nakamura - Shuichi Kodaira - Becky J Cook - Tamara Jeppson - Takafumi Kasaya - Yojiro Yamamoto - Yoshitaka Hashim

Source: https://link.springer.com/







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