The interactions between volcanic eruptions and ice and snow cover a broad spectrum from eruptions beneath ice sheets hundreds of meters thick to the melting of smaller bodies of ice or snow on volcanoes by pyroclastic deposits or lava flows (Major and Newhall, 1989; Smellie, 2000; Subglacial volcanism). A common feature of all interactions is the transfer of heat from magma to ice or snow, which leads to the production of meltwater.