Transition from locked to creeping subduction in the Shumagin region, Alaska
Article first published online: 21 MAR 2007
Copyright 2007 by the American Geophysical Union.
Geophysical Research Letters
Volume 34, Issue 6, March 2007
How to Cite
2007), Transition from locked to creeping subduction in the Shumagin region, Alaska, Geophys. Res. Lett., 34, L06303, doi:10.1029/2006GL029073., and (
- Issue published online: 21 MAR 2007
- Article first published online: 21 MAR 2007
- Manuscript Accepted: 13 FEB 2007
- Manuscript Revised: 4 FEB 2007
- Manuscript Received: 12 DEC 2006
- aseismic subduction;
- Shumagin Islands
 GPS velocities from the Alaska Peninsula are modeled to determine the extent of locking on the Alaska-Aleutian subduction interface. The observations, which span from the Semidi Islands to Sanak Island, encompass the 1938, Mw 8.3, rupture zone and the transition into the Shumagin gap. Model parameters are optimized using a simulated annealing method. Coupling variation along strike of the plate interface show a nearly fully locked (90%) subduction zone at the Semidi Islands, decreasing to about 30% locked at the Shumagin Islands, and freely slipping to the west of the Shumagins. Independent rupture of the Shumagin segment could produce repeated Mw 7.6 earthquakes, unless a significant fraction of the slip on the interface occurs as afterslip following large earthquakes. Southwest directed velocities at most of the sites may be attributed to clockwise rotation of a Bering block.