GRAVITATIONAL INSTABILITY AND PROPAGATION OF TECTONIC WAVES IN A TWO-LAYER MODEL OF THE UPPER MANTLE

Abstract

The work presents a numerical analysis of gravitational instability in a two-layer viscoelastic model and of the propagation of tectonic waves in the lithosphere-asthenosphere system. The analysis includes horizontal forces. Modes of maximum instability and rates of growth were computed for the case of density inversion. These rates increase several times with horizontal stresses, and spatial wavelengths also increase twice. In the absence of density inversion fast tectonic waves are found. Variations of their velocity are computed for several geometries and sets of physical parameters, including horizontal stress. These results can lead to a better insight into migration of large earthquakes.

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Computational Seismology, Vol. 2.