Northwestern University

Apr
10
Wed 11:00 AM

SPREE Seminar: Jean Sulem

When: Wednesday, April 10, 2019
11:00 AM - 12:00 PM  

Where: Technological Institute, A230, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students

Contact: Tierney Acott   847.491.3257

Group: McCormick - Civil and Environmental Engineering

Category: Lectures & Meetings

Description:

Multi-Physics Couplings and Strain Localization in Seismic Faults

Abstract
Field observations of exhumed mature faults and outcrops, i.e. faults that have experienced a large slip, have evidenced that shear deformation is often localized in very narrow slip zones. This strain localization is seen as the result of various weakening mechanisms induced during seismic slip. These weakening mechanisms may correspond to a mechanical degradation of the rock properties (micro-cracking, grain crushing and grain size reduction…), but various other physical processes can be responsible for it. The effect of shear heating in a fluid saturated fault zone leads to pore-fluid pressurization due to the discrepancy between the thermal expansion of water and solid grains. Chemical reactions such as dissolution/precipitation, mineral transformation at high temperature (dehydration of minerals, decomposition of carbonates, …) affect the solid phase of the rock, sometimes release a new fluid phase in the system and can induce a positive feedback in the progressive mechanical degradation. The width of the deforming zone is actually a key parameter, as narrow deforming zones concentrate the frictional heating, which leads to large temperature rises and thus to more rapid weakening. It also controls the multi-physics couplings which occur during dynamic slip. Thermo-chemo-mechanical couplings are nowadays more and more identified as factors that play a central role in the mechanical behavior and the evolution of localized deformation zones. Important challenges and questions are still open, which span from the qualitative understanding of the main phenomena to their quantitative description and observation.

In this talk, we will present some recent results on analytical and numerical modelling of strain localization processes under multi-physical couplings and discuss the geophysical implications of these instabilities for earthquakes nucleation.


Bio
Jean Sulem is Professor at Ecole des Ponts ParisTech, and Research Director. He is leading the Geotechnical Group CERMES at Laboratoire Navier. His research interests are related to Bifurcation Theory applied to stability and strain localisation analyses, Constitutive Modelling of geomaterials, Experimental Rock Mechanics, Thermo-Hydro-Mechanical Behaviour of Geomaterials with applications to Tunnelling, Petroleum Engineering, Deep Geological Storage, Fault Mechanics.

Jean Sulem is a member of the Advisory Board of several scientific journals and Associate Editor to Rock Mechanics and Rock Engineering. Since 2016, he is the President of the French Society of Rock Mechanics. In 2018, Jean Sulem received the Vardoulakis lecture Award from the University of Minnesota.

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