A 3D gravity-consistent model of the southern San Andreas Fault system

Earthquakes are a direct response to the Earth’s state of stress, which is one of the key ingredients controlling the lithosphere rheological behavior. To first order, the total in-situ stress is a function of two main co-players: the long-term tectonic stress, and the short-term (seismic cycle) stress transfer. Despite their diversity in temporal and spatial scales, these components are not mutually independent, but they do interact in the final rheological configuration of the lithosphere

Understanding the relative importance of different tectonic loads and how the stress is transferred is of high relevance for robust earthquake simulators. As the stress transferred to a fault affects its mechanical behavior, it has a direct control on its potential to generate earthquakes.

Recent studies suggest that the regional tectonic environment surrounding the faults (e.g., off-fault lithology, lithospheric structure, and degree of coupling between crustal and mantle domains) can influence fault behavior. However, the importance of such heterogeneities in modulating background seismicity needs to be properly evaluated to unveil the behavior of these complex systems.

3D data-integrative and gravity-consistent models are useful tools for characterizing such lithospheric-scale heterogeneities, and ultimately, to analyze their potential relationship with background seismicity. In this contribution, we present the preliminary results of a 3D lithospheric model of the southern San Andreas Fault system, where the wealth of available data was considered. We demonstrate that this is an important step towards the calculation of the background off fault stresses due to local loadings, which likely influence background seismicity.