The detectability of shallow slow earthquakes by the Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET) in Tonankai district, Japan

Keisuke Ariyoshi, Ryoko Nakata, Toru Matsuzawa, Ryota Hino, Takane Hori, Akira Hasegawa, Yoshiyuki Kaneda

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

In order to understand the characteristics of shallow very low-frequency (VLF) events as revealed by recent ocean-floor observation studies, we perform a trial simulation of earthquake cycles in the Tonankai district by taking the characteristics of the 1944 Tonankai earthquake and assuming that slow earthquakes occur on numerous small asperities. Our simulation results show that the increase of moment release rate of shallower VLF events in the pre-seismic stage of a megathrust earthquake is higher than that of deeper VLF events. This increase may make leveling change due to VLF swarms detectable at Dense Oceanfloor Network system for Earthquakes and Tsunamis (DONET). We also introduce the time series of hydraulic pressure data at DONET, comparing with the leveling change expected from our numerical simulation. Since leveling change due to shallower VLF swarms is so local as to be incoherent, removal of the moving-averaged data from the data stacked by four nearby observation points in the same node may be useful to detect the short-term local leveling change.

Original languageEnglish
Pages (from-to)295-310
Number of pages16
JournalMarine Geophysical Research
Volume35
Issue number3
DOIs
Publication statusPublished - 2014 Sep

Keywords

  • Earthquake cycle simulation
  • Leveling change
  • Nankai Trough
  • Very low-frequency event

ASJC Scopus subject areas

  • Oceanography
  • Geophysics
  • Geochemistry and Petrology

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