Tephra impacts on agriculture following the 2011 Puyehue-Cordón Caulle eruption

BICKERTON, HEARTHER; WILSON, THOMAS; STEWART, CAROL; CHRISTOPHER OZE; SALLY GAW; OUTES, VALERIA; VILLAROSA, GUSTAVO; BAXTER, PETER; ELISABET ROVERE

Colima

Congreso; Cities and Volcanoes 7; 2012

Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI)

The eruption of the Puyehue – Cordón Caulle volcanic complex, Chile, began on 4 June 2011 causing widespread tephra deposits across Argentinean provinces of Neuquen, Rio Negro and Chubut (covering 100,000 km2). Agriculture is an important component of Argentina’s economy; therefore, the impacts of the ashfall on this sector are of concern. Farm and emergency management interviews were conducted. The physical and chemical impacts were determined by testing of soil and tephra samples that were taken nine months after the initial eruption. Agriculture in the study region can be divided into two distinct sections; free range cattle farming in Parque Nacional Nahuel Huapi (within 40 km of the vent) and the sheep farming of fertile, semi-arid valleys (mallines) around the Ingenerio Jacobacci area (up to240 km from the vent). The first area received much coarser, thicker tephra fall (up to lapilli sized, 150-220mm thick). Livestock losses were lower than expected (around 25%), due to farmers selling off or evacuating livestock quickly and precipitation compacting and washing away tephra. The Jacobacci area received approximately 50mm of fine tephra, and experienced continued wind and water remobilisation of tephra deposits nine months after initial tephra fall. Issues were exacerbated by a six-year drought that preceded the ashfall. The total livestock losses around Jacobacci were estimated at 40-60%, birth rates were reduced by ~20% and fleece prices were depressed due to ash contamination. Preliminary results indicate that the losses sustained were due to starvation, rumen blockages and tooth abrasion causing foraging difficulties rather than chemical toxicity issues.The agricultural emergency response was not the same across all regions. Each province organised its own immediate aid before government grants were established. The development of Emergency Management frameworks and inter-province communication channels prior to the crisis would have facilitated a faster, more direct recovery. Recommendations for mitigation strategies for tephra impacts on agriculture need to incorporate differences in climate and farming practice.The eruption of the Puyehue – Cordón Caulle volcanic complex, Chile, began on 4 June 2011 causing widespread tephra deposits across Argentinean provinces of Neuquen, Rio Negro and Chubut (covering 100,000 km2). Agriculture is an important component of Argentina’seconomy; therefore, the impacts of the ashfall on this sector are of concern. Farm and emergency management interviews were conducted. The physical and chemical impacts were determined by testing of soil and tephra samples that were taken nine months after the initial eruption.Agriculture in the study region can be divided into two distinct sections; free range cattle farming in Parque Nacional Nahuel Huapi (within 40 km of the vent) and the sheep farming of fertile, semi-arid valleys (mallines) around the Ingenerio Jacobacci area (up to240 km from the vent). The first area received much coarser, thicker tephra fall (up to lapilli sized, 150-220mm thick). Livestock losses were lower than expected (around 25%), due to farmers selling off or evacuating livestock quickly and precipitation compacting and washing away tephra. The Jacobacci area received approximately 50mm of fine tephra, and experienced continued wind and water remobilisation of tephra deposits nine months after initial tephra fall. Issues were exacerbated by a six-year drought that preceded the ashfall. The total livestock losses around Jacobacci were estimated at 40-60%, birth rates were reduced by ~20% and fleece prices were depressed due to ash contamination. Preliminary results indicate that the losses sustained were due to starvation, rumen blockages and tooth abrasion causing foraging difficulties rather than chemical toxicity issues.The agricultural emergency response was not the same across all regions. Each province organised its own immediate aid before government grants were established. The development of Emergency Management frameworks and inter-province communication channels prior to the crisis would have facilitated a faster, more direct recovery. Recommendations for mitigation strategies for tephra impacts on agriculture need to incorporate differences in climate and farming practice