Vendredi 21 Février, 13H00, salle -115L
Nucleation of Earthquakes versus Slow-Slip Events : Geometrically Induced Fault Dilatancy as a Controlling Factor
An earthquake results from the fast slip that occurs along a fault surface. Interestingly, numerous dense geodetic observations of the two last decades indicate that such a dynamic slip may start by a gradual unlocking of the fault surface and related progressive slip acceleration. This first slow-slip stage is of great interest since it could define an early indicator of devastating earthquakes. However, not all slow-slip becomes fast slip, and even may simply stop. In this study, we use a numerical model based on the discrete element method (DEM) to simulate a crustal strike-slip fault of 50 km length which generates a wide variety of slip-modes, from stable-slip to slow-slip, to fast earthquakes, with similar characteristics to natural cases. The main goal of this work is to understand the conditions that allow the slow-slip events to turn into earthquakes, in contrast to those that cause slow slip events to stop. Our results suggest that the fault surface geometry and related dilatancy/contraction pattern along strike play a key role.
