Moho modeling of the Yellow Sea (West Sea) from spectrally correlated free-air and terrain gravity data

Abstract

Moho estimates for the Yellow Sea and Bohai Basin were developed from the EGM2008 gravity, ETOPO1 topography/bathymetry, and NOAA’s sedimentary thickness databases. Spectral correlation analysis between the free-air gravity anomalies (FAGA) and the terrain’s gravity effects (TGE) at 20 km altitude was made to estimate the terrain-correlated FAGA, which can provide information on the isostatic status of the study area. This study included the additional terrain gravity effects due to density contrasts from sedimentary rock thickness variations over the Yellow Sea. Spectral correlation filtering of the FAGA with the TGE estimated the terrain correlated FAGA, which were subtracted from the TGE to infer isostatically compensated gravity effects for inversion constraints on the Moho modeling. The derived Moho estimates show considerable sensitivity to the sedimentary thickness variations and tectonic features of the Yellow Sea region. In addition, the gradients in the dynamic crustal topography inferred from the terrain-correlated FAGA show apparent associations with the distribution of the Yellow Sea’s earthquakes with predominantly strike-slip focal mechanisms.