Observations made during January and April 2013 show that interactions between lava flows and snowpack during the 2012–13 Tolbachik fissure eruption in Kamchatka, Russia, were controlled by different styles of emplacement and flow velocities. Aa lava flows and sheet lava flows generally moved on top of the snowpack with few immediate signs of interaction besides localized steaming. However, lavas melted through underlying snowpack 1–4 m thick within 12 to 24 h, and melt water flowed episodically from the beneath flows. Pahoehoe lava lobes had lower velocities and locally moved beneath/within the snowpack; even there the snow melting was limited. Snowpack responses were physical, including compressional buckling and doming, and thermal, including partial and complete melting. Maximum lava temperatures were up to 1355 K (1082 °C; type K thermal probes), and maximum measured meltwater temperatures were 335 K (62.7 °C). Theoretical estimates for rates of rapid (e.g., radiative) and slower (conductive) snowmelt are consistent with field observations showing that lava advance was fast enough for aa and sheet flows to move on top of the snowpack. At least two styles of physical interactions between lava flows and snowpack observed at Tolbachik have not been previously reported: migration of lava flows beneath the snowpack, and localized phreatomagmatic explosions caused by snowpack failure beneath lava. The distinctive morphologies of sub-snowpack lava flows have a high preservation potential and can be used to document snowpack emplacement during eruptions.

Edwards, Benjamin R., Alexander Belousov, Marina Belousova, and Dmitry Melnikov. Observations on Lava, Snowpack and Their Interactions During the 2012–13 Tolbachik Eruption, Klyuchevskoy Group, Kamchatka, Russia. Journal of Volcanology and Geothermal Research, Special Issue: 2012-13 Tolbachik Eruption 307 (2015): 107-119. https://www.sciencedirect.com/science/article/abs/pii/S0377027315002668

Benjamin Edwards is a professor of Geosciences and Moraine Chair in Arctic Studies at Dickinson College.

For more information on the published version, visit Science Direct's Website. https://www.sciencedirect.com/science/article/abs/pii/S0377027315002668

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