GRSG Conference 2022: Orbit to Outcrop
Title: A new global crustal thickness model – the first seismic and gravitational unified model
Author: Mark van der Meijde
Despite 160 years of probing the world crust, due to lack of seismic and ground gravity observations, there are still white spots in the worlds’ crustal thickness map. The crustal structure in those regions is among the least understood of the Earth’s continental areas, and variations in basic but fundamental parameters – such as crustal thickness – are still poorly constrained over large areas. Recent research has shown that satellite gravity-based crustal modeling in regions with limited seismological coverage can provide unique insights in crustal thickness and underlying geodynamical processes.
In almost all of these cases the gravity signal related to crustal structure is isolated by applying 3 different corrections: topography, sediments, and upper mantle structure.
Of these three, the upper mantle correction is least well addressed. It doesn’t account for any lateral inhomogeneity upper mantle composition close to the crust-mantle boundary. As a result, satellite gravity data reductions for upper mantle structure are a source of uncertainty.
Our new model includes a new state-of-the-art upper mantle correction. By combining satellite gravity and seismic tomography, we have formulated a new methodology to integrate potential field data inversions, tomographic modelling, and petrolophysics into a single inversion scheme. Our crustal thickness model ECM2022 has therefore more accurate crustal thickness values, is seismically fitting better than previous models, and is now also consistent with gravity observations: up to a factor 100 times more accurate than e.g. CRUST1.0 and 5 times better than the GEMMA crustal model
This seismically and gravitationally unified model is the first of its kind and of great value, and importance, for geodynamical and exploration studies.