Gutenberg-Richter distributions for individual faults in California

Abstract:

Natural earthquake fault systems are highly heterogeneous in space, the result of inhomogeneities that are a function of the variety of materials of different strengths. However, despite their inhomogeneous nature, real faults are often modeled as spatially homogeneous systems. By introducing spatial heterogeneities into these models, we produced spatial and temporal clustering similar to that seen in natural fault systems, including foreshock and aftershock distributions (Kazemian et al., 2015). The implication is that the spatial and temporal patterns observed in natural seismicity are controlled by the fault structure, in addition to the triggering process. This also provides further evidence that the spatial and temporal patterns observed in natural seismicity are strongly influenced by the underlying physical properties and are not solely the result of a simple cascade mechanism (Shearer et al., 2012; Chen and Shearer, 2013; Serino, Tiampo and Klein, 2011). Here we perform a Gutenberg-Richter (GR) analysis for the major faults in southern and central California. Variability in the resulting distributions exists for not just spatially discrete faults but for different segments of larger faults. If the GR scaling and temporal variability on each fault is governed by differences in the physical properties of those faults, their distribution over the entire fault system offers an explanation for the observation of GR scaling on fault systems comprised of individual faults. It also may provide a framework to investigate variations of the GR exponent from one region to another. Those differences also provide an opportunity to compare modeled sequences to those of natural earthquake sequences from California in order to investigate the interplay between cascade dynamics and spatial structure.