Extraction of the Moho discontinuity in the Korean Peninsula and its surrounding seas using the GRACE data

The GRACE data are processed and used to investigate gravity anomalies and undulations of the Moho beneath the Korean Peninsula located at 33°43'N, 123°132'E. The gravity anomalies extracted from the GGM02S, global mean geopotential model, were adjusted on various needless components such as track noises and seasonal gravitational change effects by WCA (Wavenumber Correlation Analysis). In the study area, the adjusted GGM02S gravity anomalies range from -17.15 to 60.95 mgal. The Bouguer and Terrain corrections were operated previous to extract the Moho undulations. The values of Bouguer anomalies increase from the continent to the East Sea; this feature is related to changes in crustal thickness or shallowing of the Moho beneath the East Sea. To separate signals from above and below the Moho, the Bouguer anomalies were first subjected to a power spectrum analysis to determine the cutoff frequency range. In this study, the mean depth of the Moho calculated 26 km at Wavenumber 0.15 km-1. Undulation of the Moho was calculated from the low-frequency anomalies by 3-D inversion modeling. The Moho depth undulated in the range of -36 to -7 km. According to these results, the crustal thickness of the East Sea shows the Moho depths of approximately 15 km, and becomes progressively thicker towards the peninsula. The Korean Peninsula shows a Moho depth of approximately 30 km, which is typical of continental crust, while the Yellow and South Seas record a typical continental Moho depth of approximately 27 km. The results of the 3-D inversion modeling are in good agreement with previous other studies such as global crust model, seismic survey results, and Airy-Heiskanen isostasy model.