The 2012-2013 Seismic Swarm in the Eastern Guadalquivir Basin (S Spain)☆

Abstract The aim of the present work is a detailed study of a recent seismic swarm, which occurred in S Spain, in the eastern Guadalquivir Basin, named the Torreperogil-Sabiote seismic swarm/sequence, with specific temporal and spatial clustering properties. Based on the daily activity rate, three main phases were identified and analyzed. The released energy was estimated from the seismic moment and each one of the phases was characterized by its cumulative seismic moment. Moreover, the events of the sequence, initially located by the Spanish Instituto Geografico Nacional (IGN), have been relocated using the well-known HypoDD code. In order to derive the frequency-magnitude Gutenberg-Richter recurrence relationship, a comprehensive analysis of the completeness magnitude was performed using different approaches. All events with magnitude above the completeness magnitude (m bLg 1.5) are reported in the data. The b -value of the Gutenberg-Richter relationship was also estimated using the maximum likelihood method. Values of 1.11, 1.04 and 0.90 for the 3 considered phases in the swarm were obtained. To test retrospectively the hypothesis of b -value decrease before the occurrence of a large event, we studied its temporal variation using the overlapping moving window technique. Finally, a spatial analysis was performed using the fractal dimension, estimated using the Grassberger and Procaccia (1983) method.