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Spatial changes of inter‐plate coupling inferred from sequences of small repeating earthquakes in Japan
Author(s) -
Igarashi Toshihiro
Publication year - 2010
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 - 10.1029/2010gl044609
Subject(s) - trench , seismology , geology , slip (aerodynamics) , plate tectonics , episodic tremor and slip , subduction , pacific plate , tectonics , physics , chemistry , organic chemistry , layer (electronics) , thermodynamics
We extract sequences of small repeating earthquakes to clarify inter‐plate coupling of subducting plates over a large area of the Japanese Islands. As a result, many sequences are detected at the Philippine Sea plate subducting from the Ryukyu trench and Pacific plate subducting from the Kuril‐Japan trench. The average slip‐rates and standard deviations estimated from the sequences show substantial spatial changes of inter‐plate coupling. The large deviations of slip‐rates correspond to the occurrence of episodic slips such as after‐slips following large earthquakes. Constant slip‐rates approaching the relative plate motion indicate weak coupling areas. Slip deficits and sparse distributions of repeating groups suggest locked areas. In the Nankai trough, deep low‐frequency earthquakes in the transition zone and burst‐type repeating sequences within plates have not been located in the downdip direction of groups with slow slip‐rates. This suggests that the space‐time characteristics of inter‐plate coupling affected these seismic events.