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research article

Frictional Heating Processes and Energy Budget During Laboratory Earthquakes

Aubry, J.
•
Passelègue, François Xavier Thibault  
•
Deldicque, D.
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November 5, 2018
Geophysical Research Letters

During an earthquake, part of the released elastic strain energy is dissipated within the slip zone by frictional and fracturing processes, the rest being radiated away via elastic waves. While frictional heating plays a key role in the energy budget of earthquakes, it could not be resolved by seismological data up to now. Here we investigate the dynamics of laboratory earthquakes by measuring frictional heat dissipated during the propagation of shear instabilities at stress conditions typical of seismogenic depths. We estimate the complete energy budget of earthquake rupture and demonstrate that the radiation efficiency increases with thermal-frictional weakening. Using carbon properties and Raman spectroscopy, we map spatial heat heterogeneities on the fault surface. We show that an increase in fault strength corresponds to a transition from a weak fault with multiple strong asperities and little overall radiation, to a highly radiative fault behaving as a single strong asperity. Plain Language Summary In nature, earthquakes occur when the stress accumulated in a medium is released by frictional sliding on faults. The stress released is dissipated into fracture and heat energy or radiated through seismic waves. The seismic efficiency of an earthquake is a measure of the fraction of the energy that is radiated away into the host medium. Because faults are at inaccessible depths, we reproduce earthquakes in the laboratory under natural in situ conditions to understand the physical processes leading to dynamic rupture. We estimate the first complete energy budget of an earthquake and show that increasing heat dissipation on the fault increases the radiation efficiency. We develop a novel method to illuminate areas of the fault that get excessively heated up. We finally introduce the concept of spontaneously developing heat asperities, playing a major role in the radiation of seismic waves during an earthquake.

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Type
research article
DOI
10.1029/2018GL079263
Author(s)
Aubry, J.
Passelègue, François Xavier Thibault  
Deldicque, D.
Girault, F.
Marty, S.
Lahfid, A.
Bhat, H. S.
Escartin, J.
Schubnel, A.
Date Issued

2018-11-05

Published in
Geophysical Research Letters
Volume

45

Issue

22

Start page

12,274

End page

12,282

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
LEMR  
Available on Infoscience
January 22, 2019
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/153686
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