Interdisciplinary seismotectonic analysis in the broken foreland of the NW Argentine Andes

ZECKRA, MARTIN; AHMAD ARNOUS; ARANDA-VIANA, RODOLFO GERMÁN; EMILIO JOSE MARCELO CRIADO SUTTI; FRANK KRUEGER; STRECKER, MANFRED R.; FERNANDO HONGN

Congreso; Seismology of the Americas 2018; 2018

The extensive spatial impact of the ongoing orogenesis in the south central Andes leads to significant recent tectonic activity in great distance to the driving forces of the plate boundary. The complex multi-stage evolution of the Santa-Bárbara-System morpho-strucural province in the foreland of the NW Argentine Andes comprises reactivated inherited structures as well as Quaternary structures. The easternmost extension of the Andean deformation front is only poorly constrained yet. Recently, the need for a better understanding of the neotectonic settings for hazard and risk mitigation efforts became obvious in 2015, when a Mw 5.7 earthquake hit the town of El Galpón in the Salta Province. For this reason, we installed a local seismological network around the estimated epicenter and noteworthy geological structures. We were able to collect 15 months of continuous data from 13 stations showing a wide range of earthquake sources. Besides local crustal events, including aftershocks of the 2015 events, we also observed interplate activity underneath the Puna plateau and very deep earthquakes at approximately 600km depth. Together with the analysis of seismic-reflection lines crossing the study area we detected the fault, which is responsible for the majority of localized seismic events. In addition, for a number of suspected surface fault locations seismic-refraction and 2D electrical resistivity tomographies were carried out. The outcome from these surveys were merged with information from geological mapping and geomorphological analyses of DEMs and river networks. Thus, we can distinguish between active and non-active tectonic structures and identify their geometries. The multidisciplinary integration of geoscientific information portrays the seismotectonic setup of the easternmost margin of the NW Argentine Andes in its entirety. Thereby, this work contributes to the comprehension of the regional, large-scale processes of convergent plate margins.