Overpressured Underthrust Sediment in the Nankai Trough Forearc Inferred From Transdimensional Inversion of High-Frequency Teleseismic Waveforms

Takeshi Akuhara, Takeshi Tsuji, Takashi Tonegawa

研究成果: Contribution to journalArticle査読

4 被引用数 (Scopus)

抄録

Active-source seismic surveys have resolved the fine-scale P-wave velocity (Vp) of the subsurface structure in subduction forearcs. In contrast, the S-wave velocity (Vs) structure is poorly resolved despite its usefulness in understanding rock properties. This study estimates Vp and Vs structures of the Nankai Trough forearc, by applying transdimensional inversion to high-frequency teleseismic waveforms. As a result, a thin (∼1 km) low-velocity zone (LVZ) is evident at ∼6 km depth beneath the sea level, which is located ~3 km seaward from the outer ridge. Based on its high Vp/Vs ratio (∼2.5) and comparison to an existing seismic reflection profile, we conclude that this LVZ reflects a high pore pressure zone at the upper portion of the underthrust sediment. We infer that this overpressured underthrust sediment hosts slow earthquake activities and that accompanied strain release helps impede coseismic rupture propagation further updip.

本文言語英語
論文番号e2020GL088280
ジャーナルGeophysical Research Letters
47
15
DOI
出版ステータス出版済み - 8 16 2020

All Science Journal Classification (ASJC) codes

  • 地球物理学
  • 地球惑星科学(全般)

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