Seismicity triggered by fluid injection-induced aseismic slip

Abstract:
In the upper crust, fluid pressures are known to induce both earthquakes and aseismic deformations. However, the mechanisms involved are poorly understood and our ability to assess the seismic hazard associated with natural and anthropogenic fluid pressurization remains limited. In this talk, I will show how in-situ fluid injection experiments at meter scale can contribute to improve our understanding of how fluid pressure affects the different modes of fault slip and what it tells about the link between seismicity, aseismic creep and fluid diffusion. In our field experiments, we directly measure fault slip and seismicity induced by fluid-injection into a natural fault. The main results indicate highly dilatant and slow ([endif]-->) aseismic slip associated with a 20-fold increase of permeability, which transitions to faster slip ([endif]-->) associated with reduced dilatancy and micro-earthquakes. Mostly aseismic slip occurs within the fluid-pressurized zone and obeys a rate-strengthening friction law. Fluid-injection primarily triggers aseismic slip in this experiment with micro-earthquakes, triggered off the fluid-pressurized zone, being an indirect effect mediated by aseismic creep.
 
 
Short Bio:
I am Professor of Geophysics at the University of Nice Sophia Antipolis (France) in the Geoazur laboratory.
After a PhD in Hydromechanics (Univ. of Nice Sophia Antipolis) in 2005, I did a 2-year Post-doc at the Lawrence Berkeley National Laboratory (DOE Fellowship). In 2007, I held an Associate Professor position at the University of Nice Sophia-Antipolis in the Geoazur Earth and Planetary Sciences Laboratory. Since 2015, I am full Professor at the University of Nice Sophia Antipolis and at the Institut Universitaire de France. In 2013-2014, I was visiting Faculty for a year at CALTECH (USA) in the Tectonics Observatory (collaborations with Jean-Philippe Avouac and Pablo Ampuero). My research aims at a better understanding of the role of fluids in the mechanisms governing crustal fault and landslide dynamics, the physics of earthquakes and induced seismicity. I am interested in developing new approaches combined from geophysical observations and hydromechanical modelling for the study of coupling between fluid flow and rock deformations.