Energy partitioning and shear resistance evolution during earthquake sequences in experiments with simulated quartz gouge

Add to your list(s) Download to your calendar using vCal

• Daniel Faulkner, University of Liverpool
• Wednesday 22 January 2025, 14:00-15:00
• Wolfson Lecture Theatre.

If you have a question about this talk, please contact Adriano Gualandi.

During their lifetime, seismogenic faults will experience numerous earthquakes, with each event imparting damage onto the rocks that comprise the fault core and the surrounding country rock. The partition of energy between creating new fracture surface area, heat production, and other co-seismic processes is not well constrained and will evolve with multiple events on a fault. This evolution will have important implications for the rupture breakdown energetics in subsequent events, and also the fluid flow properties of the fault (i.e., by altering fault permeability). We investigate experimentally the evolution of fault gouge properties during multiple seismic slip events by performing a series of high-velocity slip-pulse experiments on simulated quartz gouge. The quartz gouge layers are repeatedly sheared (up to 25 slip pulses) in a high-velocity rotary shear apparatus at a maximum sliding velocity of 1 m/s for a total displacement of 0.8 m during each slip pulse. A normal stress of 10 MPa is applied to the gouge layer, while the pore fluid pressure is controlled at a constant value of 5 MPa during each experiment (i.e., effective normal stress = 5 MPa). During the sequences of high-velocity slip pulses we find that the area under the shear stress – displacement curve (sometimes called the breakdown energy) of each pulse systematically increases until a steady-state is reached after around 10 slip pulses, after which it remains constant for each subsequent slip pulse. The development of mechanical behaviour is associated with the evolution of gouge microstructure. During the first 10 slip pulses, the gouge grain size systematically reduces during each pulse as a result of the formation of submicron-sized particles, leading to an increase in the gouge surface area. However, after the first 10 slip pulses, the gouge microstructure reaches a steady-state and the gouge grain size and surface area remain approximately constant during subsequent slip pulses. Our results provide new insights on the evolution of fault gouge properties during multiple earthquake sequences and the implications this has for the partitioning of the rupture energy budget during future earthquake events.

This talk is part of the Bullard Laboratories Wednesday Seminars series.

This talk is included in these lists:

• Bullard Laboratories Wednesday Seminars
• Department of Earth Sciences seminars
• Wolfson Lecture Theatre

Note that ex-directory lists are not shown.