A regional gravimetric Moho recovery under Tibet using gravitational potential data from a satellite global model

The Moho information under Tibet Plateau is important for a better understanding of the geodynamic processes associated with the continental collision of the Indian and Eurasian tectonic plates and subsequent formation of Himalayan and Tibetan orogens. However, under the central and western parts of Tibet, the existing Moho models are still relatively inaccurate due to a sparse and irregular distribution of seismic surveys. To overcome this problem, the gravimetric data could be used to interpolate the Moho information, where seismic data are missing. In this study, we apply the gravimetric method for a regional Moho recovery under Tibet. Compared to existing methods that use either the gravity or gravity-gradient data, the method presented here utilizes a more generic definition based on a functional relation between the Moho depth and the gravitational potential. Since the gravity and gravity-gradient data have more regional support than the potential field, a numerical test is conducted to find an optimal data area extension that is needed to solve a regional inversion problem in order to reduce errors caused by disregarding the far-zone contribution. Our analysis shows that for the potential field such extension should be at least 25°, while 5° for the gravity and only about 1° for the gravity gradient. The comparison of our gravimetric result with the CRUST1.0 seismic model shows differences at the level of expected accuracy of the gravimetric method of about 5 km and without the presence of significant bias.