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SUMMARY:Catastrophic failure: sound and vision - Ian Main\, University of 
 Edinburgh
DTSTART:20250219T140000Z
DTEND:20250219T150000Z
UID:TALK228667@talks.cam.ac.uk
CONTACT:Adriano Gualandi
DESCRIPTION:Catastrophic failure is the end result of progression and loca
 lisation of damage towards brittle failure on a variety of system scales i
 n the Earth. However\, the factors controlling this evolution\, and that o
 f the resulting seismicity\, are not well constrained.  We address the qu
 estion of how to relate the two\, and the extent to which they can be cont
 rolled by feedback on the seismicity rate in a scale model experiment on a
  small rock sample deformed in a synchrotron. We image the underlying dama
 ge using x-rays and detect acoustic emissions\, and show how they change d
 uring localisation\, from distributed tensile cracking to a localised shea
 r band containing a mixture of tensile cracking\, grain rotation\, and gra
 in boundary shear\, with shear becoming increasingly dominant and ultimate
 ly frictional sliding on a contiguous fault.  We confirm that using conti
 nuous servo-control based on acoustic emission event rate not only slows d
 own deformation compared to standard constant strain rate loading\, but al
 so suppresses events of all sizes\, including extreme events. We use this 
 evolution to develop a mixture model for the stress history from damage me
 chanics\, and find it is independently consistent with the observed stress
  history and acoustic emission statistics. Our results imply that includin
 g seismic event rate control may improve risk management of induced seismi
 city compared to feedback on the maximum magnitude alone. 
LOCATION:Wolfson Lecture Theatre
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