Scaling of apparent stress from broadband radiated energy catalogue and seismic moment catalogue and its focal mechanism dependence

Abstract

Comparison between the NEIC broadband radiated energy catalogue and the Harvard CMT catalogue provides information about the properties of apparent stress. Based on the numerical studies of Shaw (1998) we examined the ratio of broadband radiated energy and scalar seismic moment of shallow earthquakes worldwide from 1987 to 1998. It is observed that for different focal mechanisms, scaling of apparent stress or ‘scaled energy’ with seismic moment is different. For thrust and normal events, apparent stress decreases with seismic moment; while for strike-slip events, apparent stress increases with seismic moment. On average, for thrust events, the apparent stress of aftershocks is higher than that of main shocks; for strike-slip events, the apparent stress of aftershocks is lower than that of main shocks; while the situation of normal events is in between.