The role of glacial isostatic adjustment in the present-day crustal motion and sea levels of East Asia

The aim of this paper is to model and remove the contribution of glacial isostatic adjustment (GIA) from the observed crustal velocities and sea-level rates in East Asia, so that the signal from other geological processes such as tectonic uplift or global change can be better revealed. State-of-the-art GIA models that include 3D variations in mantle viscosity and lithospheric thickness are employed in this study. Uncertainties of the GIA response are estimated from different ice history and background viscosity models. It is demonstrated that the uncertainties in the GIA response in East Asia are generally small compared with the response itself. For example, the land uplift rate near the east coast of China due to GIA has magnitudes of about 0.1 mm/yr while the uncertainties are generally less than 0.04 mm/yr. These are small compared with the observed magnitude of uplift rate (similar to 1.0 mm/yr) and the measurement uncertainties of GPS. For the height rates in leveling observation, relative sea-level rates in tide gauge data, absolute seal-level rates from satellite altimetry and tangential velocities from GPS data, the GIA effects are also shown to be generally small compared with observed data. This technique of cleaning geodetic data will become more useful in the future when the uncertainties of geodetic measurements can be reduced to less than 0.1 mm/yr.