Late Quaternary sea-level changes and palaeoseismology of the Bering Glacier region, Alaska

Abstract

Glacial isostatic adjustment and multiple earthquake deformation cycles produce temporal and spatial variability in the records of relative sea-level change across south-central Alaska. Bering Glacier had retreated inland of the present coast by 16 ka BP and north of its present terminus by 14 ka BP. Reconnaissance investigations in remote terrain provide new but limited insights of post-glacial relative sea-level change and the palaeoseismology of the region. Relative sea-level was above present 9.2 ka BP to at least 5 ka BP before falling to below present. It was above present by the early 20th century, before land uplift in the 1964 M 9.2 earthquake. The pattern of relative sea-level change differs what may be expected in comparison with model predictions for other seismic and non-seismic locations. Buried mud–peat couplets show a great earthquake 900 cal BP, including evidence of a tsunami. Correlation with other sites suggest simultaneous rupture of adjacent segments of the Aleutian megathrust and the Yakutat microplate.