Extracting Near-Field Seismograms From Ocean-Bottom Pressure Gauge Inside the Focal Area: Application to the 2011 Mw 9.1 Tohoku-Oki Earthquake

Tatsuya Kubota, Tatsuhiko Saito, Hiroaki Tsushima, Ryota Hino, Yusaku Ohta, Syuichi Suzuki, Daisuke Inazu

Research output: Contribution to journalArticlepeer-review

Abstract

Recent studies have shown that ocean-bottom pressure gauges (OBPs) can record seismic waves in addition to tsunamis and seafloor permanent displacements, even if they are installed inside the focal area where the signals are extremely large. We developed a method to extract dynamic ground motion waveforms from near-field OBP data consisting of a complex mixture of various signals, based on an inversion analysis along with a theory of tsunami generation. We applied this method to the OBP data of the 2011 Tohoku-Oki earthquake. We successfully extracted the low-frequency vertical seismograms inside the focal area (f < ∼0.05 Hz), although those of the Mw ∼9 megathrust earthquake had never previously been reported. The seismograms suggested two dominant energy releases around the hypocenter. The seismic wave signals recorded by the near-field OBP will be important not only to reveal earthquake ruptures and tsunami generation processes but also to conduct real-time tsunami forecasts.

Original languageEnglish
Article numbere2020GL091664
JournalGeophysical Research Letters
Volume48
Issue number7
DOIs
Publication statusPublished - 2021 Apr 16

Keywords

  • dynamic pressure change
  • ocean-bottom pressure gauge
  • seafloor ground motion
  • the 2011 Tohoku-Oki earthquake
  • tsunami

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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