Abstract
Abstract. Debris flow generation in volcanic zones in the southern Andes has not been widely studied, despite the enormous economic and infrastructure damage that these events can generate. The present work contributes to the understanding of these dynamics based on a study of the 2017 Petrohué debris flow event from two complementary points of view. First, a comprehensive field survey allowed us to determine that a rockfall initiated the debris flow due to an intense rainfall event. The rockfall lithology corresponds to lava blocks and autobrecciated lavas, predominantly over 1500 m a.s.l. Second, the process was numerically modelled and constrained by in situ data collection and geomorphological mapping. The event was studied by back analysis using the height of flow measured on Route CH-255 with errors of 5 %. Debris flow volume has a high sensitivity with the initial water content in the block fall zone, ranging from 4.7×105 up to 5.5×105 m3, depending on the digital elevation model (DEM) used. Therefore, debris flow showed that the zone is controlled by the initial water content available previous to the block fall. Moreover, our field data suggest that future debris flows events can take place, removing material from the volcanic edifice. We conclude that similar events could occur in the future and that it is necessary to increase the mapping of zones with autobrecciated lava close to the volcano summit. The study contributes to the understanding of debris flows in the southern Andes since the Osorno volcano shares similar features with other stratovolcanoes in the region.
Highlights
Landslide processes are among the most important natural hazards in developing countries due to their low resilience, generating damage to human life, property and engineering projects in all the mountainous areas of the world every year (Martha et al, 2010; Alimohammadlou et al, 2013; Sepúlveda et al, 2014; Fustos et al, 2020)
The conditions that generate debris flows were evaluated in an active volcanic zone, with reference to the 2017 Petrohué event
The 2017 Petrohué event was studied by back analysis to understand the impact of debris flows occurring on active volcanoes in the southern Andes
Summary
Landslide processes are among the most important natural hazards in developing countries due to their low resilience, generating damage to human life, property and engineering projects in all the mountainous areas of the world every year (Martha et al, 2010; Alimohammadlou et al, 2013; Sepúlveda et al, 2014; Fustos et al, 2020). Debris flows are an important type of mass wasting, described as one of the most dangerous of these processes due to their high velocity, the damage that they cause and the extensive areas affected (Jakob et al, 2005). J. Fustos-Toribio et al.: Debris Flow event on Osorno volcano present work evaluates the generation of debris flows, taking the 2017 Petrohué event as a case study. Fustos-Toribio et al.: Debris Flow event on Osorno volcano present work evaluates the generation of debris flows, taking the 2017 Petrohué event as a case study This event caused severe economic losses to one of the most popular tourist attractions in southern Chile (INE, 2018)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
