Abstract
Abstract. This paper presents the results of lahar modelling in the town of Villa La Angostura (Neuquén-Argentina) based on the Two-Phase-Titan modelling computer code. The purpose of this exercise is to provide decision makers with a useful tool to assess lahar hazard during the 2011 Puyehue-Cordón Caulle Volcanic Complex eruption. The possible occurrence of lahars mobilized from recent ash falls that could reach the city was analysed. The performance of the Two-Phase-Titan model using 15 m resolution digital elevation models (DEMs) developed from optical satellite images and from radar satellite images was evaluated. The output of these modellings showed inconsistencies that, based on field observations, were attributed to bad adjustment of the DEMs to real topography. Further testing of results using more accurate radar-based 10 m DEM, provided more realistic predictions. This procedure allowed us to simulate the path of flows from Florencia, Las Piedritas and Colorado creeks, which are the most hazardous streams for debris flows in Villa La Angostura. The output of the modelling is a valuable tool for city planning and risk management especially considering the glacial geomorphic features of the region, the strong urban development growth and the land occupation that has occurred in the last decade in Villa La Angostura and its surroundings.
Highlights
After decades of quiescence, the Cordon Caulle volcanic complex in the Chilean Southern Andes began an eruptive process at 14:45 LT on 4 June 2011 (Elissondo et al, 2011) from the new vent named “We Pillan” (New Crater in Mapuche language) (Collini et al, 2012)
In order to test the digital elevation models (DEMs), we used the initial data set for Florencia Creek
Using the radar-based DEM, the flow follows the actual natural channel hidden by the trees
Summary
The Cordon Caulle volcanic complex in the Chilean Southern Andes began an eruptive process at 14:45 LT on 4 June 2011 (Elissondo et al, 2011) from the new vent named “We Pillan” (New Crater in Mapuche language) (Collini et al, 2012). This vent is located in the Southern Volcanic Zone (SVZ) at 40.58◦ S and 72.13◦ W, and 2240 m a.m.s.l. This resulted in a lahar hazard for the town, as the snow began to melt during the spring and summer seasons. This paper analyses the hazard posed by the snow–ash deposits/pack that could contribute to lahar formation potentially affecting Villa La Angostura
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