title: Propagation style controls lava-snow interactions.
abstract: Understanding interactions between volcanic eruptions and the cryosphere (a.k.a. glaciovolcanism) is important for climate reconstructions as well as for hazard mitigation at ice-clad volcanoes. Here we present unique field observations of interactions between snowpack and advancing basaltic lava flows during the 2012-13 eruption at Tolbachik volcano, Kamchatka, Russia. Our observations show that lava-snow heat transfer is slow, and that styles of lava propagation control snowpack responses. 'A'a and sheet lava flows advance in a rolling caterpillar-track motion on top of the rigid, snowpack substrate with minor lava-snow interaction. In contrast, pahoehoe lava propagates by inflation of lobes beneath/inside the snowpack, producing rigorous lava-snow interaction via meltwater percolation down into the incandescent lava causing production of voluminous steam, rapid surface cooling and thermal shock fragmentation. The textures produced by pahoehoe-snowpack interactions are distinctive and, where observed at other sites, can be used to infer syn-eruption seasonality and climatic conditions.
authors.affiliation: Department of Earth Sciences, Dickinson College, Carlisle, Pennsylvania 17013, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: Edwards
authors.affiliation: Institute of Volcanology and Seismology, Petropavlovsk-Kamchatsky, Russia.
authors.forename: A
authors.initials: A
authors.lastname: Belousov
authors.affiliation: Institute of Volcanology and Seismology, Petropavlovsk-Kamchatsky, Russia.
authors.forename: M
authors.initials: M
authors.lastname: Belousova