Plate coupling variation and block translation in the Andreanof segment of the Aleutian arc determined by subduction zone modeling using GPS data



[1] We use GPS measurements in the first geodetic study of plate coupling on the Andreanof segment, Aleutian subduction zone. Convergence of 7.3 cm/yr at the subduction zone results in northwestward displacements greater than 1 cm/yr at stations located on the west end of the Andreanof region, but velocities at the east end are smaller in magnitude and oriented west-southwest. These velocity variations are caused by differences in plate coupling along the subduction zone, which correlate with the rupture zones of the 1986 and 1996 Mw8 earthquakes. We construct a dislocation model to estimate the velocity of the arc in the Andreanof region relative to North America, and fault plane coupling coefficients. Our best model shows a southwestward velocity of 7.8 mm/yr, a high degree of coupling in the main thrust zone at the west end of the subduction zone, and little to no coupling at the east end.