Abstract
Results obtained by the first intensive airborne surveys carried out at Volcan Villarrica (39°S) in Southern Chile, are presented. These campaigns included the use of a scanner laser system, for detecting the glacier surface topography, and a helicopter-borne ice penetrating radar, for measuring ice thicknesses. These surveys allowed determining the snow and ice volume storage at this volcano, volume which is susceptible to melt during eruptive events generating dangerous fast flows (lahars). Volcan Villarrica is one of the most active volcanoes in Chile, with frequent eruptive events, many of them associated with lahars which are considered the most hazardous process at this volcano. In fact, most of the casualties and infrastructure damages incurred during historical eruptive events at the volcano are associated with lahars. With use of the radar and laser data, a total volume of 1.17 ± 0.1 km3 of water equivalent (w.eq.) at the volcano in 2012 was calculated, only 37 % of the estimated volume of 1961, a reduction mainly explained by the area shrinkage and ice thinning rates observed in the last 51 years. This total volume represents a lower boundary available for melting during eruptive events when lahars mudflows can be generated, because mainly in the winter, nearly 0.14 km3 w.eq. are potentially added to the volcano as temporal snow falls. The volume of water equivalent lost in recent decades does not mean a lower risk associated with these flows, as there has been a huge increase in populated areas in the surroundings of the volcano in recent years.
Highlights
Several active volcanoes in the Southern Volcanic Zone (36–46°S) of Chile are partially ice capped (Stern et al 2007)
This paper describes the methods, surveys and main results obtained in recent years, providing the most updated and accurate estimation of the water equivalent volume storage
The resulting new surface topography Digital Elevation Model (DEM) covered near 50 % of the glacier area on the volcanic cone with a pixel size of 5 m and an accuracy of 0.5 m
Summary
Several active volcanoes in the Southern Volcanic Zone (36–46°S) of Chile are partially ice capped (Stern et al 2007). In spite of the importance of these glaciers located on active volcanoes, little is known about the volume of water equivalent storage and about their recent behavior in response to climate change (Rivera and Bown 2013). Based upon recent glaciological research, we know the glaciers are experiencing negative glacier mass balances (Rivera et al 2005) and, as a consequence, generalized frontal retreats are taking place (Rivera et al 2012). Few scientific studies are available concerning ice thicknesses and precise surface topography on ice capped volcanoes. Among these are Gilbert et al (1996), regarding Nevados de Sollipulli, and Rivera et al (2006) concerning Villarrica and Mocho-Choshuenco volcanoes
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