Monitoring seismic velocity change caused by the 2011 Tohoku-oki earthquake using ambient noise records

We estimated the changes in seismic velocity in the southern Tohoku district of Japan during the six‐month period centered on the 11 March 2011 Tohoku‐oki earthquake, using scattered waves retrieved by autocorrelation of ambient seismic noise. The estimated velocity decrease after the earthquake, an...

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Bibliographic Details
Published in:Geophysical research letters 2012-05, Vol.39 (9), p.n/a
Main Authors: Minato, Shohei, Tsuji, Takeshi, Ohmi, Shiro, Matsuoka, Toshifumi
Format: Article
Language:English
Subjects:
ambient noise
Bans
Earth sciences
Earth, ocean, space
earthquake
Earthquakes
Exact sciences and technology
Geophysics
Global Positioning System
Global positioning systems
GPS
Ground motion
Grounds
Monitoring
Noise
Nuclear tests
Plate tectonics
Satellite navigation systems
Scientific apparatus & instruments
Seismic activity
Seismic engineering
seismic interferometry
Seismic phenomena
Seismology
Spatial distribution
Treaties
Velocity
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Summary:We estimated the changes in seismic velocity in the southern Tohoku district of Japan during the six‐month period centered on the 11 March 2011 Tohoku‐oki earthquake, using scattered waves retrieved by autocorrelation of ambient seismic noise. The estimated velocity decrease after the earthquake, and after two large aftershocks in the study area, was as great as 1.5% in the area nearest to the mainshock. The velocity changes displayed gradual healing. The spatial distribution of the velocity change showed a correlation with both the changes in static strain, derived from GPS records, and the peak particle velocity experienced during the three earthquakes, derived from strong‐motion records. Therefore, our results show that velocity changes possibly contain information from deep in the crust bearing on coseismic stress release, in addition to shallower effects due to strong ground motion. Key Points Ambient noise data shows the crustal velocity change in Tohoku‐oki earthquake Velocity change is clearly observed at mainshock and aftershocks The velocity change is explained by both strain change and surface damage
ISSN:0094-8276
1944-8007
DOI:10.1029/2012GL051405