Tide gage measurements of uplift along the south coast of Alaska

Abstract

Annual mean sea levels along the south coast of Alaska are used to measure uplift along the Alaska-Aleutian subduction zone. The corrected sea level record should provide a measure of tectonic subsidence. In the area affected by the 1964 Alaska earthquake, postseismic uplift occurs where coseismic subsidence was observed, and postseismic subsidence occurs where coseismic uplift was observed. The immediate postseismic response is damped out within the first decade, and the subsequent uplift rates appear to be steady over the 1974-1989 interval. However, some of those rates seem to be too high to be sustained over the ~1000 year earthquake recurrence interval appropriate to this area if the interseismic deformation is only to recover the coseismic displacement. Thus a long-term (~100 years) relaxation in uplift rates is postulated. -from Authors