What can the deformation of colloids tell us about earthquake hazards?

Faults within the crust of the Earth (and other planetary bodies) evolve through the accumulation of earthquakes over thousands to millions of years. One way to understand fault evolution is by simulating crustal deformation within the laboratory using scaled materials, such as clay colloids. The scalings of length and time from the Earth’s crust to the laboratory table-top are governed by the strength and viscosity of the analog materials. With suitable rheology of analog materials, we can simulate millions of years of crustal deformation that occurs over hundreds of km within a table-top device over the course of a few hours. The evolution of laboratory fault systems captures the processes of fault initiation, propagation and linkage of faults within the Earth’s crust. One advantage of colloids over elastic materials is that stress relaxation off of faults simulates similar processes within crustal materials. The competition between stress accumulation on faults and stress relaxation off of faults modulates fault growth and earthquake recurrence. Furthermore, laboratory observations of fault slip rate variations inform estimates of seismic hazard from recent crustal fault activity