Rough faults

Rupture styles on non-planar faults

With Eric Dunham (Stanford), Yann Klinger (IPGP) and Amaury Vallage (CEA)

We often talk about “fault planes”, but did you know that natural faults are actually slightly nonplanar? This small deviation from planarity is often called roughness and measured here by the amplitude-to-wavelength ratio α. On a rough fault, local stresses are perturbed during the earthquake rupture growth, leading to rapid accelerations and decelerations of the rupture front.

I have been exploring how fault roughness affects rupture behavior (Bruhat, et al., 2016) and the produced slip distribution (Bruhat, et al., 2020).

Related publications:

Rupture complexity and the supershear transition on rough faults, Bruhat et al. [JGR, 2016]
Influence of fault roughness on surface displacement: from numerical simulations to coseismic slip distributions, Bruhat et al. [GJI, 2020]

Figure 1: Fault profiles, (middle row) slip every 0.56 s, and (bottom row) slip velocity for two extremely complex fault ruptures. Both ruptures start in the supershear regime, but either transition back or emit sub-Rayleigh pulses during their course.