Shallow earthquakes source parameters in the Eastern Sierras Pampeanas of Córdoba, (Argentina): Implications to deep crustal faulting and shortening

Abstract

In this work we propose a detailed analysis of the crustal seismicity characterizing the Sierras de Córdoba (Eastern Sierras Pampeanas, central Argentina). We considered a large number of first P- and S-wave arrivals with good azimuthal coverage by the SIEMBRA and ESP temporary seismic networks along with a regionally calibrated velocity model. We obtained accurate hypocentral solutions and related them with possible faulting basement structures. Our results indicate that the crustal seismicity of the Sierras de Córdoba is mainly concentrated to the north, west and south-west of the Sierra Grande. In addition, the seismicity at depth seems to be preferentially distributed at middle crustal levels (depths ranging from 10 to 26 km). Focal mechanisms solutions obtained from P-wave first motion polarities and P–S amplitude ratios are predominantly reverse and could be associated with the extension at depth of the Sierra de Pocho, Sierra Grande and Ciénaga del Coro faults. The magnitudes are comprised between 1.6 ≤ ML ≤ 3.3 and 1.7 ≤ MW ≤ 3.4. They represent the first estimates for small-to-moderate sized earthquakes occurring in the Sierras de Córdoba and recorded by local, temporary seismological networks.