Tomographic image of crust and upper mantle off the Boso Peninsula using data from an ocean-bottom seismograph array 4. Seismology

Aki Ito, Yojiro Yamamoto, Ryota Hino, Daisuke Suetsugu, Hiroko Sugioka, Masaru Nakano, Koichiro Obana, Kazuo Nakahigashi, Masanao Shinohara

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We determined the three-dimensional structure of the crust and upper mantle off the Boso Peninsula, Japan, by analyzing seismograms recorded by ocean-bottom seismometers and land stations between 2011 and 2013. We employed seismic tomography to determine the P- and S-wave velocity structures and earthquake locations simultaneously. The tomographic image shows that the mantle parts of the Pacific and the Philippine Sea plates have high-velocity anomalies. The upper boundary of the Philippine Sea plate is delineated as approximately 2-6 km shallower than that previously estimated from land-based data for the area 140.5°E-141.5°E and 35°N-35.5°N. A pronounced low-velocity anomaly in P- and S-waves with low-V p/V s ratio (1.5-1.6) was observed at depths shallower than 20 km in the overriding North American plate. This anomaly may be caused by the presence of rocks with a low-V p/V s ratio, such as quartzite, and the water expelled from the subducted Pacific and Philippine Sea plates.[Figure not available: see fulltext.]

Original languageEnglish
Article number118
Journalearth, planets and space
Volume69
Issue number1
DOIs
Publication statusPublished - 2017 Dec 1

Keywords

  • Boso Peninsula
  • North American plate
  • Ocean-bottom observation
  • Philippine Sea plate
  • Three-dimensional velocity structure

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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