Hipotético peligro sísmico en la estructura falla San Ramón, Chile Central

Abstract

The structure known as San Ramón fault is located at the western edge of the Andes between Mapocho and Maipo rivers. The city of Santiago is located in this area, with an approximate population of 6 million people. The urbanization and population in this area have increased exponentially. With this information it has been possible to conduct several geological, geochronological and morphological surveys (Rauld 2002, Armijo et al. 2010, Vargas y Rebolledo 2012), which results are related to the existence of a geological unit called San Ramón fault. This fact would imply a seismic hazard for the city of Santiago in this area since this structure would be in a mature state. After analyzing the research that provides information on the bedrock underground morphology, seismicity related to the large seismic events occurred in the central zone of Chile (M 6.9–7.4) which have resulted in relevant surface deformations and masswasting movements related to ground slow or rugged gravitational displacements. Besides the statistical analysis of tectonic movement in Central Chile and new information on gravimetric profiles conducted in the alleged San Ramón fault, we can come to the conclusion that such structure is just a hypothesis and any future dynamic event associated with a seismic hazard is hard to be forecasted, which if occurring, it would be related to a tectonic event within the formation dynamics of the Andes. 

It is important to highlight that the potential hazard existing in this zone is the one associated with eventual masswasting effect of occasional landslides that could be generated by relevant rainfall at the end of the most important ravines in the region: San Ramón, Apoquindo, Nido de Águila, Macul, among others.