Gravity inversion in Qinghai-Tibet plateau

Due to its high elevation and high seismicity the Qinghai-Tibet plateau takes a primary position on the earth surface. The inaccessibility of the region makes geophysical studies difficult. Active seismic sounding is available along essentially one line crossing the eastern part of the plateau. In such a situation gravity is a powerful method to obtain information on the crustal structure. We apply an inversion of the gravity field throughout the entire plateau. The inversion is limited to the long-wavelength band of the field, which has been shown by spectral analysis to be generated at lower crustal levels. The field is inverted in terms of the oscillation of a boundary layer with strong density contrast. This boundary is identified with the crust-mantle discontinuity (Moho). A map of the 3D oscillations of the Moho is presented and the properties discussed along 4 profiles cutting the plateau longitudinally and transversally.