High resolution local Moho determination using gravity inversion: A case study in Sri Lanka

• Gravity inversion is a useful tool for local Moho determination when seismic data is not adequate.
• We model high resolution Moho surface for the Sri Lankan region using gravity inversion method.
• We filter Bouguer gravity data for known short and long wavelength gravity effects before inversion process.
• The computed Moho depths are in better agreement with seismic Moho depths than those obtained by global Moho models.

The seismic data incorporated in global Moho models are sparse and therefore the interpolation of global Moho depths on a local area may give unrealistic results, especially in regions without adequate seismic information. Gravity inversion is a useful tool that can be used to determine Moho depths in the mentioned regions. This paper describes an interactive way of local Moho depth determination using the gravity inversion method constrained with available seismic data. Before applying inversion algorithms, the Bouguer gravity data is filtered in various stages that reduce the potential bias usually expected in Moho depth determination using gravity methods with constant density contrast assumption. A test area with reliable seismic data is used to validate the results of Moho computation, and subsequently the same computation procedure is applied to the Sri Lankan region. The results of the test area are in better agreement with seismically determined Moho depths than those obtained by global Moho models. In the Sri Lankan region, Moho determination reveals a fairly uniform thin crust of average thickness around 20 km. The overall result suggests that our gravity inversion method is robust and may be suitable for local Moho determination in virgin regions, especially those without sufficient seismic data.