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High interseismic coupling of the Alaska Subduction Zone SW of Kodiak Island inferred from GPS data
Author(s) -
Fletcher Hilary J.,
Beavan John,
Freymueller Jeffrey,
Gilbert Lewis
Publication year - 2001
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 - 10.1029/2000gl012258
Subject(s) - subduction , geology , global positioning system , geodetic datum , seismology , episodic tremor and slip , geodesy , slip (aerodynamics) , coupling (piping) , tectonics , mechanical engineering , telecommunications , physics , engineering , computer science , thermodynamics
We use Global Positioning System (GPS) measurements to make the first geodetic study of the Semidi segment of the Alaska‐Aleutian subduction zone. This segment, which sustained an M W 8.2 earthquake in 1938, lies between Kodiak Island where the subduction interface appears to presently be fully locked, and the Shumagin Islands segment where substantial aseismic slip occurs. We invert the GPS station velocity estimates using a nonlinear least squares algorithm to solve for the width of the locked zone, the dip, and the interseismic coupling of a model subduction interface. The data are consistent with a shallow plate interface dipping ∼6°, a locking depth of ∼23 km, and high interseismic coupling of ∼80%.