Resumen de Caracterización del movimiento de un deslizador ante tensiones normales variables y fricción rate and state regularizada
Juan Carlos Mosquera Feijoo, Beatriz García, David Santillán, Luis Cueto-Felgueroso Landeira
Earthquakes have been found to stem from stick-slip instabilities on faults. Those may happen on faults that are initially either at stationary contact or creeping. In the former case, a fault at rest needs first to reactivate, i.e., to reach some slip velocity. Unless it become arrested, the earthquake may nucleate and the seismic rupture eventually occurs. The basic principle behind the stick-slip phenomenon has widely been explained through a simple model consisting of a mass-spring slider. The injection of a pressurized fluid in the vicinity of a fault may cause its reactivation. The increasing pore pressure involves a decrease in the effective normal stresses and even the failure of the stationary contact, according to the Mohr-Coulomb criterion. In this work, we apply the slider model analogy to study the reactivation of a fault, initially at rest, when the pore pressure gradually increases due to an injected fluid. This process entails the combined effect of the effective normal stress change and the variation of the frictional strength on the fault. We use the rate- and state-dependent model including the Linker-Dieterich term to account for the effect of normal stress gradual variations on the fault frictional behaviour. We analyse the impact of the injection rate on both the frictional strength and the reactivation of the fault and identify a delay between the beginning of injections and the latter. This may explain why in actual locations, seismic ruptures have occurred long after injections ceased. Likewise, as the slip velocity is initially null, a singularity arises from the classical rate and state formulation. Here we propose a simple regularization method. We obtain some conclusions on the delayed effect of the injection rate on the fault reactivation as well as on the regularization applied for the frictional law
