Sismicidad histórica y estudios complementarios asociados a la estructura denominada Falla de San Ramón, Chile Central

Resumen

Due to the great impact that the occurrence of an earthquake over 6.9 mag- nitude would have at the Andes foothill in the central zone of Chile (Santiago), which would be under a mature stage, it was deemed necessary to do research on the fundamentals that would prove such assertion that could trigger such tectonic phenomenon. A statistical analysis was conducted on the historical earthquakes occurred in the area under research, besides refraction and gravity seismic profiles conducted perpendicularly to the possible fault trace in order to visualize the morphology of the underground bedrock. 

From the statistical analysis of the historical earthquakes occurred in the area of the supposed fault, there is no indication of a nearby epicenter in a 40 km radius. It is worth mentioning that in order to conduct a statistical analysis, a series of reliable data within the interest area is required. According to geology, the last seismic event in the area would have occurred 8000 years ago, and with this single data it is impossible to forecast future events in the area even if the most sophisticated mathematical models are used. Additionally, a morphological analysis of the Andes foothill is available, which defines that the scarp in the area is of glaciofluvial origin and not the result of the fault dynamics. 

Seismic and gravity profiles do not provide indications of a fault throw in the research area. The scarps assigned to the fault throws in the research area are attributable to mass wasting during severe winter periods in geological time. With the information provided in this study it is believed that a possible seis-mic event is unlikely to occur as result from the supposed San Ramón fault.