Deep, low-frequency microearthquakes in or around seismic low-velocity zones beneath active volcanoes in northeastern Japan

DOI Web Site Web Site 被引用文献38件

書誌事項

公開日
1994-05
権利情報
  • https://www.elsevier.com/tdm/userlicense/1.0/
  • https://www.elsevier.com/legal/tdmrep-license
DOI
  • 10.1016/0040-1951(94)90243-7
公開者
Elsevier BV

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説明

Abstract Precise hypocenter relocations have been made for shallow intraplate microearthquakes beneath northeastern Japan by applying source-region station corrections. The relocated hypocenter distribution shows that most of the events are confined to the upper 15 km of the crust which forms the brittle seismogenic zone in this volcanic arc. It also shows that exceptionally deep microearthquakes, well below the base of the seismic-aseismic boundary, occur at twelve locations of northeastern Japan. They occur in the lowermost crust or in the uppermost mantle, where rheological properties of rocks are presumed to be in the ductile regime. All the 153 events presently detected in the lowermost crust or in the uppermost mantle have anomalously low predominant frequencies (1–5.5 Hz) both for P and S waves, in contrast to those (8–20 Hz) of normal shallow events in the brittle seismogenic zone. The magnitudes of these events are small (M ⩽ 2.2). Moreover, all of these events are located beneath active volcanoes and/or near P wave low-velocity zones in the uppermost mantle. The proximity of these events to the active volcanoes and other anomalous features suggest that these deep low-frequency events are generated by magmatic activity of mantle diapirs in the uppermost mantle.

収録刊行物

  • Tectonophysics

    Tectonophysics 233 (3-4), 233-252, 1994-05

    Elsevier BV

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