Eliza S. Calder Dawn Catherine Sweeney Ruth E.C.P. Breard 2020 <div id="Abs1-section" class="c-article-section"><div id="Abs1-content" class="c-article-section__content"><p>The incorporation of snow and ice by pyroclastic density currents (PDCs) can generate mixed-avalanches and pose significant hazards at snow-clad volcanoes. Commonly, the poor preservation of these thin deposits, combined with the subtle characteristics of PDC-snow interaction, has limited their recognition in the geological record. A small-volume (2.5&nbsp;×&nbsp;10⁵&nbsp;m³), basaltic-andesite, mixed-avalanche deposit formed during the 2008 eruption of Volcán Llaima (Chile) provides insight into PDC and snow interactions. Pyroclasts accumulated on the crater rim and collapsed to form a flow that swept up to 2.8&nbsp;km from source and spread across 6.09&nbsp;×&nbsp;10⁵&nbsp;m²<span>&nbsp;</span>of the snow-clad slopes. The PDC-snow interaction at the crater rim or during flow propagation resulted in distinct deposit and pyroclast textures. These included abundant blocky non-vesicular cauliflower clasts and blocky poorly vesicular scoria. The thin and sheet-like mixed-avalanche deposit had a lumpy surface, lacked marginal levees, was very loose, and fine ash depleted. Although the flow likely incorporated snow and/or ice mechanically, the overall coarseness of the mixture precluded effective fluidization related to vaporization. Many of the features described herein are distinctive features of other mixed-avalanche deposits worldwide and should be considered key indicators of PDC-snow interaction.</p></div></div> application/pdf 10.1007/s00445-020-01413-4 en Springer The interaction between concentrated pyroclastic density currents and snow: a case study from the 2008 mixed-avalanche from Volcán Llaima (Chile) article