Seismic swarm at Punta de Vacas, Frontal Cordillera of Mendoza: Analysis of the June–July 2019 seismic events.
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Abstract
The northern sector of Mendoza Province is classified by the Instituto Nacional de Prevención Sísmica (INPRES) as one of the most seismically hazardous regions of Argentina. Nevertheless, the western margin of the Frontal Cordillera at the latitude of Mendoza City is generally characterized by low crustal seismicity and by the absence of structures with recognized neotectonic activity. Here we present a seismological analysis of a sequence of crustal earthquakes (Mw 2.7–3.9) reported by INPRES in the vicinity of Punta de Vacas (Frontal Cordillera
of Mendoza) between latitudes −32.7° and −32.9° and longitudes −69.7° and −70.0°, recorded during June–July 2019 after a 24-year
interval of very low seismicity in the area. These events were felt by residents of Las Cuevas, Punta de Vacas, Polvaredas, Uspallata, and even Mendoza City, raising concern particularly among the communities closest to the epicenters. Identifying seismogenic sources in this region is essential for assessing seismic hazard along National Route 7—an area of major logistical and touristic importance that connects Argentina and Chile through the Los Libertadores International Pass. Relocation of hypocenters and focal-mechanism determinations indicate that the recorded activity constitutes a seismic swarm aligned with the Las Vacas lineament, although its triggering mechanism remains unresolved.
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