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We calculate the gravity anomalies due to lateral changes in bathymetry from an independent topography compilation, and those due to changes in sediment thickness and density. To obtain the Moho depth and the crustal thickness of the South China Sea basin, the 3‐D gravity inversion method is employed, based on an “initial model of fluctuating interface” constrained by the control points from seismic data and sonobuoys. And then, the gravity data is corrected for the lithospheric thermal gravity anomaly within continental margin due to lithosphere thinning. Over most of the South China Sea basin, the Moho depth ranges between 8∼14 km, the crustal thickness is 3∼9 km. The NNE trending fossil spreading center of the East and the Southwest Basin extend to 112°E, the Moho depth is more than 12 km, the crustal thickness is above 6 km in the spreading center. However, the crust of the spreading center at the northwest basin is not obviously thickened. In the northern margin of the southwest basin, south of Zhongsha block, there is a crustal thinning belt, nearly EW trending, where the crustal thickness is about 9∼10 km. The 14 km isoline of the Moho depth and the 9 km isoline of the crustal thickness are very close to the Continent‐Ocean Boundary.

The effective elastic thickness (Te) of the lithosphere is a proxy for mechanical strength and can be used to constrain lithospheric rheology and understand how surface deformation relates to deep Earth processes. Here, we map Te variations over the Pacific Ocean from the inversion of the admittance between free‐air gravity anomaly and bathymetry data calculated using a continuous wavelet transform, taking both surface and subsurface loads into account. The Pacific lithosphere show Te ranging between 0 and 80 km with a mean of 13.5 km and a standard deviation of 12.3 km. We find that Te is generally poorly correlated with plate loading age, crustal age, heat flow and Curie point depth, except for relatively young (<60 Ma) and warm lithospheres. Most oceanic plateaus and seamounts show Te≤10 km, with the lowest values (<5 km) around active spreading centers. The highest Te estimates (>30 km) are found along subduction zones and around the Hawaiian‐Emperor Seamount Chain (HESC). Taken together, these results support a temperature control on Te for small loads and warm lithosphere through steady‐state creep processes, but strain hardening operating at large plastic strain and low temperature could explain high Te associated with large‐amplitude and long‐wavelength loads (subduction zones and the HESC) and should be incorporated in yield strength models of oceanic Te.

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