Crustal seismicity and the earthquake catalog maximum moment magnitude (Mcmax) in stable continental regions (SCRs) Correlation with the seismic velocity of the lithosphere

A joint analysis of global seismicity and seismic tomography indicates that the seismic potential of continental intraplate regions is correlated with the seismic properties of the lithosphere. Archean and Early Proterozoic cratons with cold, stable continental lithospheric roots have fewer crustal earthquakes and a lower maximum earthquake catalog moment magnitude (Mcmax). The geographic shear-velocity perturbations (dVS) relative to the Preliminary Reference Earth Model (PREM). We compare dVS at a depth of 175 km with the locations and moment magnitudes (Mw) of intraplate earthquakes in the crust (Schulte and Mooney, 2005). Many intraplate earthquakes concentrate around the pronounced lateral gradients in lithospheric thickness that surround the cratons and few earthquakes occur within cratonic interiors. Globally, 27% of stable continental lithosphere is underlain by dVSZ3.0%, yet only 6.5% of crustal earthquakes with Mw44.5 occur above these regions with thick lithosphere. No earthquakes in our catalog with Mw46 have occurred above mantle lithosphere with dVS43.5%, although such lithosphere comprises 19% of stable continental regions. Thus, for cratonic interiors with seismically determined thick lithosphere (1) there is a significant decrease in the number of crustal earthquakes, and (2) the maximum moment magnitude found in the earthquake catalog is Mcmax1⁄46.0. We attribute these observations to higher lithospheric strength beneath cratonic interiors due to lower temperatures and dehydration in both the lower crust and the highly depleted