Camilla Cattania

While power-law distributions in seismic moment and interevent times are ubiquitous in regional catalogs, the statistics of individual faults remains controversial. Continuum fault models typically produce characteristic earthquakes or a narrow range of sizes, leading to the view that the regional statistics originates from interaction of multiple faults.
I present theoretical arguments and numerical simulations demonstrating that seismicity on homogeneous planar faults can span several orders of magnitude in rupture dimensions and interevent times, if the fault dimension W is sufficiently large compared to a characteristic length Lcrit, related to the nucleation dimension. Large faults are increasingly less characteristic, with the fraction of system-size ruptures proportional to (Lcrit/W)^1/2. Earthquake statistics for large W/Lcrit is remarkably close to nature, exhibiting Omori decay and power-law distributed rupture lengths. Simple crack models are consistent with a Gutenberg-Richter distribution with b=3/4, and provide a physical basis for these distributions on individual faults.