Edwards, Benjamin R. and Tuffen, Hugh and Skilling, Ian P. and Wilson, Lionel (2009) Introduction to special issue on volcano-ice interactions on Earth and Mars : the state of the science. Journal of Volcanology and Geothermal Research, 185 (4). pp. 247-250. ISSN 0377-0273
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Abstract
The study of volcano-ice interactions, also referred to as ‘glaciovolcanism’ (e.g., Kelman et al., 2002), has become an important topic of scientific research over the past 30 years, even though its study goes back to the early 1900s (Peacock, 1926; Noe-Nygaard, 1940; Mathews, 1947; van Bremmelen and Rutten, 1953). Four important themes drive this increasing importance: volcano hazard awareness and prevention, the Pleistocene global climate record, potential feedbacks between deglaciation and volcanism, and Martian geoscience research. As awareness, assessment and mitigation of environmental hazards becomes a dominant theme around the world, much attention has focused on hazards associated with snow and ice-covered volcanoes (e.g., 2009 eruptions at Nevado del Huila in Columbia and Redoubt volcano in Alaska). The disaster at Nevado del Ruiz in 1985 was a wake-up call for the world community of disaster planners as it demonstrated that even relatively small eruptions at such volcanoes can lead to significant hazards (Major and Newhall, 1989). Such hazards are widespread, occurring at a large number of volcanoes in the North and South American Cordilleras, the northwest Pacific, Iceland and elsewhere. The potential for the sudden generation and release of large quantities of meltwater at snow- and ice-covered volcanoes, either as lahars (e.g. Nevado del Ruiz) or jökulhlaups (e.g. Gjálp) is the major concern. Although hazards from volcano-ice/snow interactions are increasingly recognized by emergency planners, especially in Iceland (e.g. Eliasson et al., 2006) and the United States (e.g. Till et al., 1993), awareness and mitigation strategies elsewhere have room for significant improvement. Secondly, volcanoes that have interacted with ice may provide a unique record of changing Pleistocene ice thicknesses, which is invaluable for improving palaeo-climatic reconstructions (e.g. Smellie et al., 2008). One of the chronic problems of glacial geology is providing absolute timing constraints to differentiate periods of terrestrial ice advance and retreat. New glacial advances tend to destroy evidence of previous ones, as many of the depositional units (e.g. till and moraines) are not well preserved in areas of active ice movement. Two exceptions to this are the records preserved by glaciomarine sediments and glaciovolcanic deposits. Marine sediment cores provide a detailed chronology of ocean temperatures over the last 2.5 Ma, but this record is not easily correlated with changes in land-based ice. Products of volcano-ice interactions are increasingly playing a critical role in establishing the terrestrial record for palaeo-ice conditions. Pioneering work, especially in Antarctica (Smellie et al., 2008), is combining volcanological information on glacier extents and thicknesses with high precision geochronology to map out such fluctuations. Recent studies of glaciovolcanism in Iceland (Carrivick et al., 2009; Licciardi et al., 2007; McGarvie et al., 2006; Stevenson et al., this issue; Tuffen and Castro, this issue) are beginning to yield important new information on the mid-Pleistocene chronology of ice advance and retreat immediately south of the Arctic Circle. In western North America, work is advancing to constrain the pre-LGM positions of the Cordilleran ice sheet (Edwards et al., this issue) as well as the local effects of ice advances further south on isolated Cascade volcanoes (Lodge and Lescinsky, this issue). Future work in these areas will provide critical constraints allowing us to better determine how changes in ocean temperatures are translated into changes in terrestrial ice, enabling us to better understand how ice sheets and glaciers respond to global climatic change. Convincing evidence is accumulating to indicate that past changes in the thicknesses of ice sheets have affected the activity of volcanoes beneath them in a variety of volcanic and tectonic settings (e.g. Jellinek et al., 2004; Maclennan et al., 2002; Nowell et al., 2006). The thinning and withdrawal of major ice sheets during the last glacial-interglacial transition ~11 ka ago lead to a dramatic acceleration in magma production and eruption in Iceland by a factor of 30 (Maclennan et al., 2002). Sub-ice volcanic activity may impact the stability and mass balance of ice sheets, primarily by facilitating basal sliding due to the production of meltwater and deformable volcanic debris (Blankenship et al., 1993; Bourgeois et al., 2000; Vogel and Tulaczck, 2006). Positive feedback, where receding ice triggers volcanism that encourages ice recession, may therefore have been important in the past and may be important in the future as ice rapidly thins in volcanic areas such as the West Antarctic Ice Sheet (WAIS), Iceland and the Andes. Indeed, 20th century thinning of Iceland’s Vatnajökull icecap may have led to an acceleration in recent volcanism in central Iceland (Pagli and Sigmundsson, 2008). A decrease in planetary albedo due to deposition of dark tephra onto the surface of ice and snow (Wilson and Head, this issue) may further amplify any positive feedback. Finally, scientists are using information from terrestrial volcano-ice interactions to study our closest planetary neighbour Mars, as many features on Mars are similar to terrestrial glaciovolcanic landforms (Allen, 1979). More recently, increasingly detailed data from Mars has provided further evidence that volcano-ice interactions have been commonplace (Chapman et al., 2000; Smellie, 2009), and areas of volcanically-triggered melting are the most likely niches for Martian life (Cousins et al., 2009). Meanwhile new types of terrestrial glaciovolcanic landform are being documented (e.g. Edwards et al, this issue; Skilling, this issue, Tuffen and Castro, this issue) that may help us to identify more Martian glaciovolcanic deposits.