Incident Factors in Seismic Vulnerability and Urban Planning: Recommendations for the Puente Alto Masterplan Modification in the face of the Risk of the San Ramón Fault

The San Ramón Fault, of the active crustal type, is located in the foothills of Santiago running from north to south through the municipalities of Lo Barnechea, Vitacura, Las Condes, La Reina, Peñalolén, La Florida, Puente Alto, and Pirque. This situation is complex, because Chilean regulations NCh433.Of1996 “Seismic design of buildings” (Instituto Nacional de Normalización [INN], 1996) and NCh2369. Of2003 “Seismic design of structures and industrial facilities” (INN, 2003) do not consider the presence of geological faults, which are neither incorporated in the Metropolitan Masterplan nor in the corresponding municipal masterplans. The threatened area in Puente Alto is one of the zones expected to suffer the greatest damage due to the acceleration of this fault, and is less urbanized than in the other districts. This research aims to identify the factors incidental to seismic vulnerability in order to recommend regulatory adjustments to the Puente Alto Municipal Masterplan in this area, as this would have a greater preventive effect than in the other municipalities. For this purpose, a mixed approach is used that includes semi-structured interviews with professionals specialized in seismic risk and urban planning, as well as the analysis of current planning instruments. The results show that the main incident factor in vulnerability is land use, for which classification of uses is proposed according to their level of criticality. It is concluded that it is possible to adjust the Puente Alto Municipal Masterplan, reducing the seismic risk associated with the San Ramón Fault.