Global sub-crustal stress field

Abstract

The sub-crustal stress has been traditionally computed using the Runcorn's formulae.This method allows computing the stress field only with a very limited spectral resolution.To overcome this problem, we apply a new method of computing the sub-crustal stress components based on utilizing the stress function with a subsequent numerical differentiation.This method increases the (degree-dependent) convergence domain of the asymptotically-convergent series and consequently allows evaluating the stress components to a higher spectral resolution compatible with currently available global crustal models.This method also facilitates the variable Moho geometry, instead of assuming only a constant Moho depth in the Runcorn's formulae.The crustal thickness and the subcrustal stress are then determined directly from gravity and (seismic) crustal structure models.The numerical result reveals that the largest intensity of the sub-crustal stress occurs mainly along seismically active convergent tectonic plate boundaries, particularly along oceanic subduction zones and continent-to-continent collision zones.