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SUMMARY:Coseismic damage near active faults : a laboratory perspective
DTSTART:20171117T121500
DTEND:20171117T131500
DTSTAMP:20260920T172525Z
UID:cf44330195d2a7d4623161e084d85d8cd16047d2510b663339727aff
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Dr Mai Linh Doan\, ISTerre\, University of Grenoble\, Fr
 ance\nAbstract : Earthquakes are generated by the fast propagation of slip
  along active faults.The faults are not a pure sharp discontinuity but are
  borded by a damage zone\, that witnessed the history of the fault growth\
 , tectonics loading and previous earthquakes. The latter is of great inter
 est for the study of previous earthquakes but it needs to be discriminated
  from static damage. That’s why we pioneered a series of experiments to 
 find markers of dynamic damage. \nTo do so\, several rocks were loaded wi
 th Split Hopkinson Pressure Bars. We found that at strain rate\, crystalli
 ne rocks tend to fragment in finely grained rocks but the accumulated stra
 in is so small that the initial rock structure is preserved. This is simil
 ar to the pulverised rocks found in the field.The high strain needed to cr
 eate this pervasive diffuse damage suggest an exceptionally high strain ra
 te shaking\, which is important for seismic hazard assessment. By repeatin
 g loading\, a similar phenomenon occurs\, but the threshold is only reduce
 d by half. \nBesides being promising for paleoseismic studies\, the study
  of dynamic damage reveals appealing properties for the coseismic damaged 
 rocks\, with a sharply reduced sonic velocity and a strongly enhanced perm
 eability\, which can strongly affect the hydromechanical properties of act
 ive faults.\n\nBio : Mai-Linh Doan is assistant professor at ISTerre\, an 
 Earth Sciences laboratory of Université Grenoble-Alpes. She majored in ph
 ysics at ENS Paris and then switched to geophysics to works on the mechani
 cs of active faults (PhD in IPG-Paris and postdoctoral stay at UCLA and UC
 SC). She combines in situ observation of the hydromechanics of fault zone 
 through scientific drilling and borehole geophysics\, with laboratory rock
  mechanics experiments. Especially\, she works to identify how the dynamic
  loading of earthquakes can produce markers of dynamic damage that can be 
 used as marker of previous large earthquakes.
LOCATION:GC C3 30 https://plan.epfl.ch/?room=GCC330
STATUS:CONFIRMED
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