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Numerical investigation of the impact of fluids on the earthquake cycle

Applicant Simpson Guy
Number 184626
Funding scheme Project funding (Div. I-III)
Research institution Section des Sciences de la Terre et de l'environnement Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Geophysics
Start/End 01.10.2019 - 30.09.2023
Approved amount 259'661.00
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All Disciplines (3)

Discipline
Geophysics
Geology
Other disciplines of Earth Sciences

Keywords (5)

modelling; FEM; earthquakes; faulting; fluids

Lay Summary (French)

Lead
Modélisation numérique des interactions fluides-séismes
Lay summary
Ce projet vise à mieux comprendre la relation entre fluides, séismes et déformation dans la croûte en utilisant les simulations numérique.
Direct link to Lay Summary Last update: 29.03.2019

Responsible applicant and co-applicants

Employees

Name Institute

Abstract

Fluids are ubiquitous in the upper crust and are strongly suspected to play animportant role in the weakness of some faults, earthquake triggering, earthquakeswarms and slow earthquakes. However, our understanding of these phenom-ena and of the role of fluids in earthquakes and faulting is hindered by strongtransient changes in fluid pressure over the seismic cycle and by our inabilityto directly measure these variations at depths where most earthquakes are nu-cleated. Further difficulties arise due to the highly non-linear nature of thecoupled problem and to the large disparity in time scales (from seconds to hun-dreds of years) governing the various physical and chemical processes that giverise to fluid pressure variations. These features are formidable to resolve in thefield and laboratory and have so far been insufficiently addressed in theoreticalstudies.Here I propose a comprehensive study of the role of fluids on earthquakesspanning time scales from single ruptures to multiple events based on numericalmodeling. Our study will be based on integration of modern concepts of earth-quake mechanics on rate- and state-frictional faults with porous flow driven bya combination of buoyancy, pressurisation at depth (e.g., due to a fluid source),coseismic permeability enhancement and postseismic permeability reduction.Our main objectives are (1) to determine how the presence of overpressured flu-ids impact on rupture characteristics and recurrence compared to ’dry’ modelsand (2) to better understand coupled interactions between fluid flow and defor-mation over the duration of the seismic cycle. Our results should help bettercomprehend the differences in slip styles on different faults, along with the stressstate in the upper crust and the mechanics of weak faults.As part of this research grant, I request 4 years of funding for one new PhDstudent to be based within the Department of Earth Science at the University ofGeneva, working under the guidance of the PI, Dr. Guy Simpson. The projectwill also involve interaction with Drs. Matteo Lupi and Joel Ruch (Universityof Geneva), along with Dr. Steve Miller (University of Neuchâtel).
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