In this work a physical model is presented which describes the behavior of spontaneous rupture events (earthquakes) which dynamically propagate in a fault zone in the presence of molten material, produced by the friction between the surfaces in contact. First a solution is derived for the temperature within the layer of molten material. Then this solution is incorporated into a numerical code for solving the fundamental problem of elastic dynamics. When a melt layer is produced the classical Coulomb friction is not ? more valid, but the behavior of the fault zone ? described by a viscous rheology.
The results of the theoretical model are in agreement with data derived from exhumed faults. Furthermore, it is shown that the fault, after having experienced a first release of stress (controlled by the constitutive law of the slip-weakening which initially describes the fault), further releases stress (this time controlled by the exponential type weakening which characterizes the viscous type rheology). Does this further fall in effort increase the degree of instability? of the fault, increases the speed? of propagation of the earthquake and the fracture energy.
Caption Figure - Results of the proposed model in a generic fault point. (a) Time evolution of traction on a fault. (b) Phase portrait (traction as a function of sliding speed). (c) Comparison between the theoretical results described by the model (black and gray curves) and data derived from exhumed faults (blue circles)
Journal of Geophysical Research, Vol. 116, B02310, doi:10.1029/2010JB007724, 2011
Journal LINK: http://www.agu.org/journals/jb/
Dynamic seismic ruptures on melting fault zones
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