Since October 2012 till now, more than 2200 low magnitude earthquakes have been located in the vicinity of the towns of Torreperogil and Sabiote (Jaén), in the easternmost part of Guadalquivir Basin, Spain, an area considered of low seismic hazard. Specific tectonic studies in the region are barely available due to the scarce deformation of Mesozoic and Cenozoic cover. However, the reinterpretation of former seismic reflection profiles reveals blind faults in the Variscan basement that could host the swarm.
In this work we show the characteristics of the seismic series, including the relocation of earthquakes with magnitude above mbLg 1.5 using the well-known HypoDD code. In addition to a disperse seismicity composed by very low magnitude events that could not be relocated, two clear seismicity clusters with different characteristics were observed. Both clusters showed an approximate
N-S striking, probably related to two N-S striking structures. Additionally, we also assessed a statistical analysis of the sequence.
The detailed survey carried out in the epicentral area verified the existence of some fault zones. Although it is also possible to observe dip-slip movements, the main zone shows a tectonic fabric with lateral sense of shearing. Their strike and kinematics are in agreement with one of the two nodal planes of the computed focal mechanism.