Coseismic changes in subsurface structure associated with the 2018 Hokkaido Eastern Iburi Earthquake detected using autocorrelation analysis of ambient seismic noise

Hiroki Ikeda, Ryota Takagi

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Autocorrelation analysis using ambient noise is a useful method to detect temporal changes in wave velocity and scattering property. In this study, we investigated the temporal changes in seismic wave velocity and scattering property in the focal region of the 2018 Hokkaido Eastern Iburi Earthquake. The autocorrelation function (ACF) was calculated by processing with bandpass filters to enhance 1–2 Hz frequency range, with aftershock removal, and applying the one-bit correlation technique. The stretching method was used to detect the seismic wave velocity change. After the mainshock, seismic velocity reductions were observed at many stations. At N.AMAH and ATSUMA, which are located close to the mainshock, we detected 2–3% decreases in seismic wave velocity. We compared parameters indicating strong ground motion and showed the possibility of correlations with peak dynamic strain and seismic velocity reduction. We also investigated the relationship between waveform correlation and lag time, using ACFs from before and after the mainshock, and detected distortion of the ACF waveform. The source of the waveform decorrelation was estimated to be located near the maximum coseismic slip, at around 30 km depth. Thus, distortion of the ACF waveform may reflect the formation of cracks, due to faulting at approximately 30 km depth.[Figure not available: see fulltext.].

Original languageEnglish
Article number72
Journalearth, planets and space
Volume71
Issue number1
DOIs
Publication statusPublished - 2019 Dec 1

Keywords

  • Ambient noise
  • Autocorrelation function
  • Hokkaido Eastern Iburi Earthquake
  • Scatterer distribution change
  • Seismic interferometry
  • Seismic velocity changes

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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