Crustal Thickness Variation in Southern China and Adjacent Areas Using High-Accuracy Constrained Nonlinear Density Interface Inversion Methods

Abstract:

Southern China and adjacent areas sample through several complex tectonic units. Damaging large earthquakes and other geohazards happen very frequently in this region. Mapping crustal thickness and studying lithospheric structure and dynamics of this region are really important. Various receiver function analyses are routinely applied to map discontinuities in the Earth’s crust and mantle primarily in a station-by-station fashion. Deep active-source seismic soundings are done along some profiles. These passive and active seismic results provide useful constraints and verifications for 3D or 2D inversions of more easily available potential-field data though.

We advance new high-accuracy 3D and 2D methods for constrained nonlinear density interface inversions. Synthetic numerical model tests show that: the new nonlinear methods are stable and noise-resistant; comparing to the exact, the inversion results derived from the new methods are more accurate than those of the popular conventional methods. In this region there are several notable Moho interface depth gradient belts, which correspond to deep faults. The gravity-based crustal thickness variation is reasonably compatible with other geophysical and geological information.