The influence of local environmental and socio-economic conditions on the impacts of ash storms

FORTE, P.; DOMINGUEZ, L.; BONADONNA, C.; LAMBERTI, M.C.; GREGG, C.; BRAN, D.; CASTRO, J.M.

Nápoles

Conferencia; Cities on Volcanoes 10; 2018

IAVCEI

Ash storms have increasingly been reported in different areas around the world during the last decade (e.g., Alaska, Iceland and Patagonia). The recent volcanic ash wind remobilization events related to 2010 Eyjafjallajökull and 2011- 2012 Cordón Caulle deposits demonstrated that remobilized ash is a widespread and long-lasting hazard. In particular, the 2011-2012 Cordón Caulle (Chile) eruption emitted about 1 km3 of rhyodacitic tephra, which due to the dominant westerly winds in the region was mainly deposited in neighboring Argentina. In addition to the impact of primary tephra fallout during the eruption, a vast area of the Argentinian Patagonia (from the Andes Range to the coast) was also significantly affected by wind-remobilization of ash even several years after the climactic phase of the eruption. In this study, we characterize the phenomenology and assess the impacts of ash storms associated with the deposits of this eruption by combining tools of natural and social sciences. Specifically, we focus our analysis in two contrasting farming communities showing different environmental (i.e., precipitation regime, vegetation cover and structure, topography), socio-economic (i.e., farming activities, land use, ethnic composition) and primary tephra deposit (i.e. thickness and grain size) characteristics. Our study areas included the farming community of Villa La Angostura, located in the Andes Range at ~50 km from Cordón Caulle and Ingeniero Jaccobacci, located in the Patagonian steppe ~250 km from the vent. We investigated the impact of ash storms on the farms and their productive activities, but also on the farmers? emotions. Our findings revealed a large influence of pre-existing local environmental and socio-economic conditions on the frequency, intensity and extension of this long-lasting secondary hazard and in itsassociated impacts. Furthermore, our results provide valuable information necessary for future development and implementation of mitigation and land use planning strategies.