Debris flow event on Osorno volcano, Chile, during summer 2017: new interpretations for chain processes in the southern Andes
<p>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 debri...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-10-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://nhess.copernicus.org/articles/21/3015/2021/nhess-21-3015-2021.pdf |
| Summary: | <p>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 <span class="inline-formula">4.7×10<sup>5</sup></span> up to
<span class="inline-formula">5.5×10<sup>5</sup></span> m<span class="inline-formula"><sup>3</sup></span>, 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.</p> |
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| ISSN: | 1561-8633 1684-9981 |