In this paper a one-dimensional analytical model for the mechanism of rock fracturing in hydrothermal regimes is described. The model is based upon the modern thermo-poro-elasticity theory and its two non-linear heat-like equations. On the boundary aquifer-caprock a buried thermo-mechanical source is supposed to be built up in terms of subsurface fluid-rock coupling dynamics. With this considerations it is assumed that fluid pore pressure approaches the breakdown pressure of the caprock such that this starts failing. In order to study rock fracturing the variability of fluid-rock thermal diffusivity and fluid diffusivity at the onset of rock failure is taken into account in the two non-linear heat-like equations. A series of fluid-rock temperature and fluid pore pressure shock wave fronts is obtained as a solution of Burgers' equation. These fronts, moving through the caprock as propagating fractured boundaries, are referred to as thermo-mechanical fracture shock waves. It is found that the speed of thermomechanical fracture shock waves propagation and their amplitude are governed by a coefficient I, whose value depends on the role played by fluid-rock thermal diffusivity and fluid diffusivity variations. As a result, the final effect of thermomechanical fracture shock waves is the migration of the top of the aquifer towards a shallower depth with associated increases in the superficial thermomechanical outputs. Moreover, if thermomechanical fracture shock waves are maintained from below by the arrival of other waves, the fractured boundary can further migrate upwards and eventually trigger a catastrophic event such as a phreatic eruption.

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