Geodetic analysis of post-seismic crustal deformations occurring in South Korea due to the Tohoku-Oki earthquake

Abstract

Despite its low frequency of resident earthquakes, the Korean Peninsula is indirectly affected by the large earthquakes occurring in the Japanese Islands. In this study, GPS coordinate time series were analyzed to examine the changes in the crustal movement of the Korean Peninsula due to the 2011 Tohoku-Oki (TO) earthquake. A comparison of the pre- and post-seismic crustal deformation velocities indicated that the crustal movements of the Korean Peninsula had a velocity of 29 mm/year and an azimuth of 113° before the earthquake, and a velocity of 36 mm/year and an azimuth of 108° after the earthquake. Therefore, the crustal movement velocity significantly increased, and the direction of the movement headed more eastward compared to that before the earthquake. The calculation of the progress rate of the post-seismic crustal deformation after eliminating the Euler pole velocity and annual cycle signal from the coordinate time series showed that about 80% of the total post-seismic crustal deformation had progressed in the Korean Peninsula. In addition, analysis of principal strain change indicated that for the principal strain applied to the Korean Peninsula, the east-west dilatation increased and the north-south contraction decreased compared to those in the co-seismic stage.