Census indicators as a tool to assess social vulnerability to ashfall events in Argentina: the case of Villa La Angostura during the 2011 Cordón Caulle eruption

DELMÉNICO, AGUSTÍN; VILLAROSA, GUSTAVO; BEIGT, DÉBORA; OUTES, VALERIA; ANDRADE, MARÍA ISABEL; MANZONI, CAROLINA

Puerto Varas

Congreso; Cities on Volcanoes 9; 2016

Sernageomin

Socialvulnerability is defined by the socio-economic conditions previous to acatastrophic event. The June 2011 eruption of Puyehue-Cordón Caulle VolcanicComplex caused a strong impact in several towns located in the Nahuel Huapiregion, particularly in Villa La Angostura (VLA), located ~50km downwind fromthe vent. Economic activities, transports, communication systems and serviceslike water supply and energy supply were severely affected. Themethodological strategy consisted of to select a set of socioeconomicindicators provided by the 2010 National Census of Population and Housing wereused to assess the social vulnerability of VLA in relation to the consequencesof the Cordón Caulle eruption. This census was carried out eight months beforethe eruption, providing the information about previous social conditions.Also, the spatialresolution used was the minimum spatial information unit called ?radio censal?.The selected indicators were analyzed in order to perform a vulnerability map, inwhich the most susceptible neighborhoods were identified. The results obtained wereexamined together with information about the response actions taken during theemergency. Government support provided to the population was directed mainly tothe more vulnerable neighborhoods according to the map of vulnerability. The applicationof this method allows Civil Protection agencies to anticipate especially vulnerablesites to ash fall impacts, considering housing conditions and drinking watersupply system as main indicators. After the 2011 eruption revealed considerablyhigh vulnerability in several aspects, a series of improvements were performed (e.g.in the drinking water supply and distribution systems). Finally, some of theanalyzed variables, like roof materials and their sloping angles are keyfactors in the assessment of the vulnerability to eruptive events and otherphenomena like heavy snowfalls in Northern Patagonia.