Localized seismicity in the San Rafael block area, Argentina

Abstract

Seismicity registered in the southern region of Mendoza (34.5°S to 36°S and 67.5°W to 70°W), Argentina, has been reported in this work. Data were obtained from a seismological network composed by 12 station (San Rafael Block “BSR” Experiment). A total of 177 seismic events are presented with a nearly continuous distribution with depth. From this work, we observed that the Nazca subducting plate is seismically active up to depth of approximately 230 km. At depths less than 35 km few seismic events are located in San Rafael Block and adjacent zones; only some of them could be related to “Las Malvinas” fault. Additionally, intermediate-depth seismic events associated to the lithospheric mantle are presented. This seismicity could be related to dehydration of the mantle wedge minerals, considering that those minerals are stable under certain pressure and temperature condition. Then, when those conditions are altered, the dehydration occurs. The ascent of an asthenospheric mantle plume in the adjacent region could favor these changes in the stability conditions of the minerals, producing mineral dehydration and consequently the intermediate located seismicity. This seismicity has not been reported previously by other networks and constitutes new evidences of seismicity in the region.