Outline of recent research on ice-volcano interactions in Southern Chile
Abstract
Glaciers in Southern Chile (34 - 46°S) are mainly located on top of active volcanoes. The majority of these glaciers have only recently been inventoried and their areal and frontal changes are only partially documented. Most of these glaciers have receded and shrank in recent decades. The main driving factor explaining the glacier retreat is thought to be atmospheric changes, however in some cases the cause is the impact of the volcanic activity. In order to understand better the different driving mechanisms and responses, several surveying campaigns have been conducted to a selected group of ice-capped volcanoes, including the use of an airborne Light Detection and Ranging (LIDAR) system, equipped with visible and thermal infrared cameras, and the use of a helicopter borne radio echo sounding system (Radar). The LIDAR system measured the surface topography of the glaciers at sub metric accuracy, allowing the orthorectification of the simultaneously collected aerial photographs. The radar system has been able to penetrate the total thickness of the ice, mapping the bedrock topography as well as the bed power reflection. The 25 active ice-capped volcanoes analyzed in this work have a total ice area in year 2011 of 500 km2, and despite local differences, generalized area shrinkage and frontal retreats were detected with a total ice area lost of almost 200 km2 in the last 35 years. Among these volcanoes, most of the surveys have been conducted at Volcanes Palomo (34.61°S/70.29°W), Hudson (45.90°S/72.97°W) and Villarrica (39.41°S/71.93°W), where digital elevation models (DEMs) were generated as well as high resolution visible and thermal infrared mosaics. The DEMs comparisons have allowed the estimation of mean ice thinning rates up to 2 m/yr at the glacier ablation areas. A maximum ice thickness of 190 m was measured at Volcán Villarrica, where a total volume of water equivalent of 1.45 km3 was estimated. The strongest volcanic activity impact on glaciers was detected at Volcán Hudson, where a LIDAR survey performed before and after the most recent eruption of October 2011, yielded a maximum vertical ice loss of 74 m inside the caldera surrounding newly borne parasitic volcanic cones. This area suffered a widespread ice destruction producing several lahar pulses, generating a strong ice thinning at the main outflow tongue of Glaciar Huemules, the ice body infilling the caldera. These strong glacier changes are superimposed on a general atmospheric temperature increase and precipitation reduction detected at low altitude meteorological stations. However, very little is known about atmospheric changes at the altitude where glaciers are located, due to the lack of automatic weather stations. In spite of this problem, a couple of stations located on ice-capped volcanoes have revealed strong warming events not registered at low altitudes, indicating that atmospheric warming may be even stronger near the glacier equilibrium line altitudes. Much more research is needed to better understand the complex ice-volcano-atmosphere interactions in this region.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMGC44A..02R
- Keywords:
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- 0776 CRYOSPHERE / Glaciology;
- 8408 VOLCANOLOGY / Volcano/climate interactions;
- 9360 GEOGRAPHIC LOCATION / South America