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Tidal triggering of earthquakes prior to the 2011 Tohoku‐Oki earthquake ( M w 9.1)
Author(s) -
Tanaka Sachiko
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl051179
Subject(s) - geology , seismology , foreshock , remotely triggered earthquakes , tidal force , seismic gap , induced seismicity , aftershock , physics , astronomy
I observe highly significant tidal triggering of earthquakes prior to the 2011 M w 9.1 Tohoku‐Oki earthquake. Strong statistical correlations between tidally‐induced stresses and earthquake occurrence times are identified in the northern part of the Tohoku‐Oki source region, where the mainshock rupture initiated, in the several to ten years before the Tohoku‐Oki earthquake. The tidal phase distribution of earthquakes in this period exhibits a peak where the shear stress is at its maximum to promote failure. On the other hand, no significant tidal correlation is found after the Tohoku‐Oki mainshock. These observations suggest that tidal triggering occurs over a decade‐long period preceding the Tohoku‐Oki earthquake, and the initial rupture site of this event is already critically stressed in this precursory stage.