Crustal tilting derived from Holocene sea‐level observations along the east coast of Hokkaido in Japan and upper mantle rheology

Abstract

Late Holocene sea‐level observations at sites along the east coast of Hokkaido in Japan indicate a gradual decrease of the altitude of relative sea‐level eastward toward the tip of Nemuro Peninsula. These observations in seismically active areas can be explained by glaciohydroisostatic adjustment due to the last déglaciation for an Earth model with a thin lithosphere of 30–40 km thickness and with no low viscosity layer, or with a 25 km lithosphère overlying a low viscosity layer less than 50 km, although more data as a function of time are needed to distinguish these models. Thus the vertical crustal displacement associated with the subduction of the Pacific plate seems to has not been cumulated on a time scale of 103–104 years.