Fault Mechanics Webinar Friday March 31: Ice friction and healing under dynamic loading conditions


Ice friction and healing under dynamic loading conditions
Christine McCarthy, Lamont Doherty Earth Observatory of Columbia University

Antarctic ice streams that exhibit stick-slip events sufficient to generate seismic waves are demonstrating velocity weakening behavior as defined by rate- and state- dependent friction. Healing between events is a necessary condition of stick-slip. We have conducted laboratory experiments to better constrain healing and frictional stability in a simplified ice-on rock system, quantifying the relevant parameters via velocity steps and slide-hold-slides. In particular, we measure healing rates that are orders of magnitude greater than typically measured in rock friction experiments. Additionally, oscillatory velocities were used to explore the role of tidal modulation on friction and healing and rate-state values obtained can be used to forward model to dynamic systems. [more info] [register]


What can we learn about friction evolution and rupture behavior from laboratory experiments?
Vito Rubino, Ecole Central de Nantes

Characterizing the rheology of faults is of paramount importance to improve our understanding of frictional ruptures and earthquake physics, as friction controls key processes of rupture nucleation, propagation, and arrest and also influences how damaging earthquakes can be. In this presentation, I will describe the evolution of frictional strength during the propagation of dynamic ruptures using laboratory experiments. Our innovative experimental approach allows us to capture the full-field evolution of particle velocities of dynamic ruptures and decode the nature of friction by tracking its evolution and studying its dependence on slip, slip velocity and their history. We find that friction evolution is consistent with the rate-and-state friction laws combined with flash heating weakening mechanism but not with the widely used slip-weakening laws. Our recent experiments along interfaces enriched with fault gouge, the pulverized rock present in natural fault, reveal an even more complex behavior characterized by intermittent rupture propagation. The measured friction behavior allows us to challenge existing friction laws and formulate new ones. This approach gives a new perspective on the study of friction and provides important insights into earthquake and rupture physics. [more info] [register]

See our website for a full list of talks in the Fault Mechanics Webinar Series running through June 2 [webinars]