Analysis of neotectonic structures in the Eastern Precordillera of Argentina in relation to seismic hazard by the application of integrated geophysical methods

• Published in: Tectonophysics 2018-03, Vol.728-729, p.23-33
• Main Authors: Correa-Otto, Sebastián, Ariza, Juan, Lince Klinger, Federico, Giménez, Mario, López Hidalgo, Andrés
• Format: Article
• Language: English
• Subjects: Andean Precordillera; Area; Deformation; Earthquakes; Electric contacts; Geological hazards; Geology; Geophysical exploration; Geophysical methods; Geophysics; Gravimetry; Magnetic permeability; Magnetic susceptibility; Magnetism; Magnetometry; Neotectonic structures; Neotectonics; Seismic activity; Seismic hazard; Surveys; Synclinal folding; Thermogravimetric analysis
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2018.02.005

The city of San Juan, in the Central-Western region of Argentina, has been the target of very destructive superficial earthquakes, some of which have not been associated to a clear structural source up to this date. The city is constantly growing outside the valley where it is located, towards the area of Eastern Precordillera which is currently having an increased socio-cultural activity. Thus, this study is focused on increasing the geological knowledge of the latter by studying the eastern flank of Sierra Chica de Zonda (Eastern Precordillera) whose proved neotectonic activity represents a geohazard. On the basis of the general geological setting the neotectonic structures in the study area are related to a major active synclinal folding located just under the western sector of the San Juan city. Geophysical potential methods (gravimetric and magnetometric surveys) were used to recognize contacts by contrast of density and magnetic susceptibility. In order to reduce the ambiguity of these methods the gravi-magnetometric results were constrained by using seismic and electrical tomographies. These contacts where geophysical properties abruptly change, were interpreted as faults despite many of them not having a superficial expression. The latter being of great importance to asses the seismic hazard of the study area. •Geological study of the local Quaternary deposits•Integration and combined interpretation of several geophysical methods•Reverse fault system found linked to major active synclinal folding•Seismological hazard related to neotectonic activity on a poorly studied area•Modelling of blind faults as possible sources of seismic site effects