Spatiotemporal Variation of Tectonic Tremor Activity Before the Tohoku-Oki Earthquake

Satoshi Katakami, Yoshihiro Ito, Kazuaki Ohta, Ryota Hino, Syuichi Suzuki, Masanao Shinohara

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

A slow slip event (SSE) and tectonic tremors occurred approximately 1.5 month prior to the occurrence of the 2011 Tohoku-Oki earthquake near the Japan Trench. Although we cannot completely rule out other sources of noise near the observation site, slow earthquakes would demonstrate the nucleation of a fast slip event from prior slow earthquake activity. Here we report on tectonic tremor activity detected from short-period ocean-bottom seismometer (OBS) data with a modified frequency scanning method that allows robust tectonic tremor detection by incorporating information from multiple frequency passbands in order to suppress false detections. We have identified at least five tectonic tremor sequences on the OBS records from the end of January 2011 to just before the occurrence of the Tohoku-Oki earthquake in March 2011. To reveal the spatial distributions of tectonic tremors before the Tohoku-Oki earthquake, we then calculated tremor energy, with corrected site amplification, from the identified tectonic tremor time window at each OBS that detected tremors. Possible sources of tremors were distributed in trenchward side of the SSE fault prior to the main shock. These tremors could be modulated by SSE to take into account consistent timing between tremor and SSE term, and consistency of spatial locations between estimated tremor sources and SSE faults. This spatiotemporal pattern in tectonic tremor activity demonstrates a significant separation of occurrence sources between tectonic tremors and regular earthquakes.

Original languageEnglish
Pages (from-to)9676-9688
Number of pages13
JournalJournal of Geophysical Research: Solid Earth
Volume123
Issue number11
DOIs
Publication statusPublished - 2018 Nov

Keywords

  • Tohoku-Oki earthquake
  • frequency scanning method
  • ocean bottom seismometer
  • shallow tectonic tremor
  • slow earthquake

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'Spatiotemporal Variation of Tectonic Tremor Activity Before the Tohoku-Oki Earthquake'. Together they form a unique fingerprint.

Cite this