Short- and long-term evacuation of people and livestock during a volcanic crisis: lessons from the 1991 eruption of Volcán Hudson, Chile

Abstract

Human and livestock evacuation during volcanic crises is an essential component of volcanic risk management. This study investigates the evacuation of human and livestock populations from areas impacted by ashfall from the 1991 Hudson eruption, Patagonia. The eruption was one of the largest in the 20 th century resulting in significant impacts on rural communities in affected areas, including the evacuation of people and livestock. In the short-term (<3 months), evacuation of people from farms and rural towns was driven primarily by ashfall and ash storm impacts on public health and essential services. Severe impacts on livestock and the inability to restore vegetation growth following pasture burial, also meant pastoral farming became unsustainable in the short term. This resulted in evacuation of farms for usually <1, but up to 4 years following the ashfall and subsequent intense ash-storms. In areas of very heavy ashfall (>1 m) or where agricultural systems were stressed (from drought and long-term low commodity prices) many farms were abandoned, resulting in permanent migration of the farm population. Farms and farmers under pressure from marginal economic returns were the least likely to cope with the 'shock' of the ashfall. The financial capacity of farmers was important in their resilience and ability to return once conditions improved, although emotional attachment to the land sometime outweighed financial considerations. Evacuation of livestock in areas affected by ash falls was undertaken by many farmers, but it was not very successful or economically justifiable. Access for livestock trucks to the impacted area was difficult due to a poor road network, ashfall and snow induced blockage, and remobilised ash inhibiting visibility. The lack of reliable records of livestock populations inhibited evacuation and efforts to supply supplementary feed to the remaining livestock. The very poor condition of livestock prior to the eruption and burial of feed following the eruption often made evacuation uneconomic as well as reducing livestock resilience to cope with the eruption and transport impacts. The lack of capacity within the local livestock market and lack of available grazing land for the influx of transported livestock were also key failings of the evacuation effort.

Chronology and impact of the 2011 Cordón Caulle eruption, Chile

“…Similarly to the CC eruption, a massive loss of sheep (1 million) and cattle (about a thousand) in Argentina and Chile was estimated, due to burial of vegetation from tephra, water contamination and animal poor health conditions. As in the case of CC eruption, Wilson et al (2010Wilson et al ( , 2012) also reported animals with gastrointestinal affections, teeth abrasion, blindness, immobilization and dehydration. Impact on vegetation varied according to the thickness of the tephra deposit.…”

“…The impact of this eruption, very similar to that described for the CC eruption, included big economic losses in Patagonia, mainly from the impact on livestock and crops, air traffic disruption and water contamination. As in CC, Wilson et al (2010Wilson et al ( , 2012) also reported interruptions and disruptions in electricity and water supply, accumulation of pumice in lakes over a long period of time, abrasion and weathering of machinery and electrical devices. An important psychological-social impact in the population was also recorded, combined with the abandonment from farms and towns (in Puerto Ibañez, Chile, the spontaneous evacuation of people was gradual, reporting a decrease of 30 % from a starting population of 4000).…”

“…Blong, 1984Blong, , 2003Hampton et al, 2015;Jenkins et al, 2014;Johnston et al, 2000;Magill et al, 2013;Martin et al, 2009;Milazzo et al, 2013;Stewart et al, 2006;Wardman et al, 2012;Wilson et al, 2010Wilson et al, , 2011aWilson et al, , 2012Wilson et al, , 2013. In this study, we compile data from various sources to reconstruct a precise chronology of the local and regional impacts that followed the 2011 CC eruption.…”

Risk reduction through community-based monitoring: the vigías of Tungurahua, Ecuador

“…Although active volcanoes can pose threats to the populations living around them, fertile soils, equable climates and increasingly the livelihoods afforded through tourism can exert a strong pull (Tobin & Whiteford 2002;Kelman & Mather 2008;Wilson et al 2012). Coupled with human attachment to place and community (Dibben & Chester 1999), this means that people may have compelling reasons to live with the risks associated with volcanoes.…”

Introducing Geoscience Students to Numerical Modeling of Volcanic Hazards: The example of Tephra2 on VHub.org

“…Model outputs include the mass of tephra accumulation, in units of kg m -2 , and a binned distribution of particle sizes calculated as weight percent of the total mass at specific locations around the erupting volcano. The mass per unit area is often directly used in hazard forecasts, since mass loading by tephra affects infrastructure resilience (Wilson et al 2012). Small particle sizes directly affect air quality (due to resuspension of particles in the atmosphere); they also increase an area's susceptibility to flooding (tephra can dramatically impact infiltration rates of meteoric water into the ground; Blong 1984).…”