¿Urbanización fallada? La Falla San Ramón como nuevo escenario de riesgo sísmico y la sostenibilidad de Santiago, Chile

Abstract

Santiago de Chile, habitada por cerca de 7 millones de personas, se ubica a los pies del flanco occidental de la Cordillera Principal de Los Andes, uno de los cordones montañosos más activos de nuestro planeta. La zona oriente de Santiago ha experimentado una expansión urbana sin precedentes en las últimas cuatro décadas, generando un aumento de la exposición de sus habitantes a riesgos socio-naturales de origen geológico, entre ellos la posibilidad de terremotos corticales asociados a la Falla San Ramón. El presente trabajo explora este nuevo escenario de amenaza sísmica, utilizando cartografía especializada a partir de cinco estados de avance claves para la ciudad, impulsados por políticas urbanas nacionales e instrumentos de planificación intercomunal desde 1960 hasta la actualidad. Los resultados muestran que esta urbanización acelerada ha alcanzado un 55% de la traza en superficie de la falla, lo cual no ha sido considerado en las regulaciones. Se concluye en la necesidad de avanzar en los vacíos normativos a través de la articulación de la amenaza sísmica natural con el medio urbano, como base para la reducción del riesgo de desastres y un desarrollo sostenible que considere además las inequidades de la urbe.

An interdisciplinary study of the seismic exposure dynamics of Santiago de Chile

“…In terms of urban planning, the current lack of tools and mechanisms to prevent further urbanization and occupation of risk-prone areas, such as the trace of the SRF, also entails an immediate challenge for implementing changes in the corresponding risk governance, institutions, and planning tools (Vargas Easton et al 2018). Furthermore, the impacts of an earthquake in the SRF would be mostly local (i.e., at city level) unlike what happens with large subduction earthquakes which often reach a national scale, further stressing the urban risk governance capacities and institutions.…”

“…Recent hazards research for Santiago has focused on characterizing the San Ramón fault (SRF) and the soils of the city to produce and update seismic hazard maps (e.g., Rauld et al 2015). The SRF runs across Santiago for more than 30 km, and evidence of its activity has only started to be produced since 2004 (Vargas Easton et al 2018). The characterization of the fault and its rupture potential are still in their early stages.…”

“…The characterization of the fault and its rupture potential are still in their early stages. However, it has been estimated that the SRF could produce an earthquake with magnitude up to MW 7.5 and local accelerations up to three times larger than those experienced in the MW 8.8 Maule earthquake from 2010 (Vargas Easton et al 2018). In the case of vulnerability, research is slowly shifting from the characterization of structural elements to the development of analytical and empirical fragility curves for structures (e.g., Cabrera et al 2018).…”

“…However, the natural phenomena under study are mostly related to water in the context of flooding (e.g., Banzhaf et al 2013) and socio-environmental conflicts (e.g., Aliste and Stamm 2017;Romero et al 2012). Only a recent work by Vargas Easton et al (2018) presents a multi-disciplinary study addressing Santiago's growth under the recent evidence of seismic activity in the SRF. The authors have estimated that ca.…”

“…The authors have estimated that ca. 45% of the SRF trace has not been yet urbanized, proposing that regulatory changes should be enacted to preserve the current urbanization level near the fault's trace to mitigate the potential impacts of a future earthquake (Vargas Easton et al 2018).…”