On the rapid postseismic uplift along Turnagain Arm, Alaska following the 1964 Prince William Sound earthquake

Abstract

An analysis of leveling data obtained along Trunagain Arm, Alaska in the aftermath of the 1964 Prince William Sound earthquake shows that the postseismic uplift reate was constant during the first year following the earthquake. The maximum 1-yr peak-to-trough uplift was about 15 cm, while the maximum uplift relative to a tide guage site in Anchorage was about 9 cm. There is some evidence for a modest decrease in the ulplift rate between May and October of 1965, although the evidence is weakened by the lack of an appropriate reference point. The longer term temporal evolution of uplift rates, as compiled from leveling, GPS, tide gauge, and VLBI observations by Cohen [1966], can be modeled by an Omori-like or exponential transient decay curve with a time constant of several years. The geodetic data, taken in conjunction with seismological constraints, can be explained by aseismic-slip-at-depth along the tectonic plate interface with an initial slip rate of 35 cm/yr and a slip depth of 25-37 km.