Morphometry of the historic fault scarp identfied north of Cerro La Cal, La Cal Fault Zone, Mendoza

Abstract

Morphometric and historic paleoseismic research was conducted in northern Mendoza in order to characterize and quantify the geomorphic evidences of historic surface rupture identified on the northern part of the La Cal fault zone. Integration and interpretation of multidisciplinary data and information strongly suggest that the identified historic surface rupture was associated with the devastating Mendoza Earthquake occurred in 1861. The historic surface deformation occurred almost entirely along an older prehistoric scarp, by a combination of thrust faulting and nearsurface folding. Two low-relief historic slope elements were recognized on the composite Villavicencio Sur scarp, which differ from the typical sequence of forms developed on historic normal-fault scarps. The remnant of free face, the upper slope element, and the collapse slope, the lower slope element, are controlled by the internal friction and by gravity and the sliding friction of the alluvial material, respectively. The historic paleoseismic method discussed here appears to be particularly useful in the time period covering most of the historical records kept for earthquakes in Argentina, the last 350 years, in which most of the absolute dating methods are not very effective.