Glaciers and volcanoes studies in Southern Chile

Volcanological studies in Southern Chile



Volcanological studies in Southern Chile have mainly focused on geological, geochemical and flow dynamics characteristics of the main active volcanoes, their products and recent eruptions, including their eruptive histories, effusion rates, pyroclastic flows, lava flow dynamics, mud flow deposits and associated volcanic hazards (e. g. Lara, 2004; Clavero and Moreno, 2004; Moreno and Clavero, 2006; Moreno, 1993 and 2000;Castruccio et al., 2006). However, most of human volcanic-related casualties in the region have been caused by lahars rather than other volcanic processes such as lava flows (e.g. Naranjo and Moreno, 2004). Therefore,the study of the volume of water equivalent storage on active volcanoes in southern Chile is highly necessary.Moreover, the recent and still ongoing eruptive event at Chaitén volcano, southern Andes, is an example of the destructive power of lahar flows, in this latter case triggered by rainfall. In this sense, ice and snow covering active volcanoes should be an important issue in terms of risk assessment, as during eruptive events, even of small magnitude, large volumes of snow/ice can potentially melt and flow downstream as lahars (e.g.Johannesson, 2002), sometimes causing unbelievable damages (e.g. Nevado del Ruiz eruption in 1985;Naranjo et al., 1986). Although recent studies (Naranjo and Moreno, 2004; Castruccio, 2005; Castruccio et al.,2006) have tried to estimate lahar deposit volumes, the latter with the aim of modelling possible future inundation areas, there is still the problem of underestimation of the real volume of the original flow. Castruccio et al. (2008) have started to modify available modelling softwares, such as LAHARZ, in order to estimate the volume of the original flow and its relation with the resulting deposit. However, for a better evaluation of different inundation areas associated to possible future eruptive scenarios, more precise estimations on glaciervolumes at ice-capped volcanoes are needed.

 

Glacier studies in Southern Chile have predominantly focused during recent decades on historical records(Lliboutry, 1956 and 1998), glacier inventories (Rivera, 1989), frontal variations (Rivera et al., 2002), ice area changes (Rignot et al., 2003), energy balance (Brock et al., 2007) and surface mass balance (Bown et al.,2007). For that purposes, they have used techniques widely tested in other glacial regions, e.g. remotely sensed imagery analysis (Paul et al., 2002; Hall et al., 2000; Williams, et al., 1997), DEM generation and comparison (Toutin and Cheng, 2001; Hirano et al., 2003; Kaab, 2002; Rivera et al., 2005B) and radio echo FONDECYT 2007 NATIONAL RESEARCH FUNDING COMPETITION 3 sounding surveys (Copland and Sharp, 2001; Gades et al., 2000). Nevertheless, some Chilean glaciological problems have been only preliminary studied, like the properties of the bed underneath the glaciers (especially on ice-capped volcanoes), the glacial hydrology and the effects of edifice deformations on ice-cappedvolcanoes.

 

Referencias

 

 

BOWN, F.; RIVERA, A.; ACUÑA, C. and CASASSA, G. 2007. "Recent glacier mass balance calculations at Volcán Mocho-Choshuenco 40°S Chilean Lake District" Glacier Mass Balance Changes and Meltwater Discharge, IAHS Assembly in Foz Iguaçu, Brasil. p.143-152

 

CASTRUCCIO, A. and VARGAS, G. 2005. "Lahares generados por la erupción de 1971, en el flanco occidental del volcán Villarrica, Andes del Sur".

 

LARA, L. E.; NARANJO, J. A. and MORENO, H. 2004. "Rhyodacitic fissure eruption in Southern Andes ( Cordón Caulle, 40.5°S) after the 1960 Chilean earthquake : a structural interpretation". Journal of Volcanology and Geothermal Research, 127-138.

 

LLIBOUTRY, L. 1956. "Nieves y Glaciares de Chile: Fundamentos de Glaciología". Ediciones de la Universidad de Chile. Santiago, Chile. 471 p.

 

MORENO, H. and CLAVERO, J. 2006. "Geología del área del volcán Villarrica, Regiones de la Araucanía y de los Lagos. Servicio Nacional de Geología y Minería". Carta Geológica de Chile, Serie Geología Básica, 21.

 

RIVERA A. 1989. "Inventario de glaciares entre las cuencas de los ríos Bio Bío y Petrohué su relación con el volcanismo activo : caso Vn Lonquimay". Tesis Universidad de Chile. p.199.