Seismicity and Quaternary Deformation in the Lerma Valley, NW Argerntina

EMILIO SUTTI; CAROLINA MONTERO-LOPEZ; FERNANDO HONGN; FRANK KRÜGER; GERMAN ARANDA-VIANA; MARTIN ZECKRA; MANFRED R. STRECKER

Berlin

Congreso; YES; 2019

The Lerma Valley is the easternmost intermontane basin of the southern Cordillera Oriental in the Central Andes. The Cordillera Oriental is tectonically driven by thick-skinned deformation with thrusts faults rooted at the Neoproterozoic-Cambrian basement and exhuming at the surface in the core of high elevation mountain ranges; besides reactivated normal faults formed during the Cretaceous Rift. It is limited to the West by the Altiplano-Puna plateau and to the East by the Sierras Subandinas and the Santa Bárbara system. The whole mountain range system defines a tectono-structural province who exhibits double vergence.Ongoing mountain uplift results in seismic activity, like historical (e.g. 1930 M7, La Poma) and recent (2010 MW 6.3) destructive earthquakes. The latter occurred at the central-western part of the Lerma Valley and left one dead.To unveil hidden active structures a complete and detailed investigation of the crustal seismicity of the valley is carried out using continuous data from a temporary seismological network (LEVARIS), with twelve 3-component seismometers. The overall operation period of this network covered 13 months. The event localization and magnitude estimation is performed using HYPOSAT (2016d). Further, scattering and amplification phenomena (caused by the basin fill) will be studied using 2.5D C-based programs, starting with synthetic seismograms construction. The aim of the work is to correlate microseismic events clustering with the active structures within or near the valley which are leading to recent deformation.