SCEC2023 Plenary Talk, Fault and Rupture Mechanics (FARM)

Looking to fault-rupture experiments for inspiration

Robert C. Viesca

Oral Presentation

2023 SCEC Annual Meeting, SCEC Contribution #12859
Relatively small-scale laboratory experiments have proven to be fertile grounds for ideas to interpret seismological and geodetic observations made in the field. In some instances, lab experiments provide the principal observation of phenomena that previously were only theoretically known to be possible, or even theoretically thought not to exist. Examples in this vein include past observations of shear (mode-II) fracture propagating faster than the shear wave speed of the material being ruptured, and more recently, supershear propagation in opening (mode-I) fractures. The lesson has been that surprises abound, and it helps to have an abundance of useful data. In this talk we’ll highlight a few of the ways controlled experiments have helped and may help illuminate how frictional rupture can occur seismically and aseismically, using examples from cm-scale triaxial compression of pre-cut rock samples; as well as the nucleation, propagation, and arrest of seismic ruptures within decimeter-scale blocks of PMMA and meter-scale blocks of rocks. These experiments provide proofs of concept of what fault rupture behavior can be adequately resolved and a foundation for larger-scale (decameter) field experiments inducing rupture on natural faults. We’ll briefly examine a few observations of natural fault behavior at much larger scales and look to tie them back to ideas generated on the basis of experiments.