Dr. Enrico Milanese, a postdoctoral associate in MIT ERL/EAPS, presents "Origins and evolution of geometrical heterogeneities in frictional systems: model materials and geological faults" as part of the EAPS Geophysics Seminar.

"Friction and fracture are closely related phenomena, and, in both cases, the mechanical response of the system depends on the geometrical and mechanical properties of the interface and the bulk. Heterogeneities in these properties thus affect the system response. In rocks, roughness influences the sliding behaviour at all scales, from stress changes in laboratory rock experiments to nucleation and propagation of earthquakes on geological faults. In turn, faults and fractures originally form in a heterogeneous rock structure that thus affects their final geometry.

Here, I will present my contributions to the topic of formation and evolution of geometrically heterogeneous interfaces. In the first part I show, by means of extensive atomistic simulations, the role of wear, interfacial adhesion, and scale-dependent deformation mechanisms in driving a model system to exhibit the same fractal morphology that is observed in faults. I will then move to the origins of off-fault fracture during earthquakes, focusing on the 2019 Ridgecrest sequence, and I will show that the final fault geometry is the result of a multi-scale process, where small tensile fractures coalesce along shear planes.

Seminar in Geophysics (12.571) is a class for EAPS graduate students in geophysics. All members of the MIT Community are welcome to join for presentations by guest speakers which will take place approximately every two weeks during the spring semester on Tuesday mornings 10am in 54-209 and on Zoom. Titles and abstracts for talks will be posted here when available."