Temporal Evolution of Radiated Energy to Seismic Moment Scaling During the Preparatory Phase of the Mw 6.1, 2009 L'Aquila Earthquake (Italy)

We investigate the preparatory phase of the 2009, Mw 6.1 L'Aquila earthquake in central Italy by analyzing the temporal evolution and spatial distribution of the seismic moment, M-0, to radiated energy, E-S. Our approach focuses on monitoring the deviations of the scaling between M-0 and E-S with respect to a model calibrated for the background seismicity. The temporal evolution of these deviations, defined as Energy Index (EI), identifies the onset of the activation phase 1 week before the mainshock. We show that foreshocks are characterized by a progressive increase in slip per unit stress, in agreement with the diffusion of highly pressurized fluids before the L'Aquila earthquake proposed by previous studies. Our results suggest that the largest events occur where energy index (EI) is highest, in agreement with the existing link between energy index (EI) and the mean loading stress.

Automated summary

We investigated the preparatory phase of the 2009 L'Aquila earthquake by analyzing the relationship between seismic moment and radiated energy. Our findings showed a correlation between energy index and seismic activity.