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Evidence of stress relaxation caused by time-dependent deformation in the damage zone of the Chelungpu fault system
  • Mayukh Talukdar,
  • Hiroki Sone
Mayukh Talukdar
University of Wisconsin-Madison

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Hiroki Sone
University of Wisconsin-Madison
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High fracture density in fault damage zones not only reduces the elastic stiffness of rocks but may also promote time-dependent bulk deformation through the sliding of fracture surfaces and thus impact the stress evolution in fault zones. Comparing the damage zones of the three faults in the Chelungpu fault system encountered in the Taiwan Chelungpu fault Drilling Project (TCDP), the youngest damage zone showed pronounced sonic velocity reduction even though fracture density is the same for all three fault zones, consistent with the shorter healing time of the youngest fault. Caliper log data showed a time-dependent enlargement of the borehole wall at the damage zone. These damage zones record lower differential stress than the surrounding host rock, which cannot be explained by the reduced elastic stiffness in the damage zone. Stress relaxation caused by time-dependent bulk deformation in the damage zone may be responsible for the observed low differential stress.
07 Sep 2023Submitted to ESS Open Archive
11 Sep 2023Published in ESS Open Archive