No abstract

No abstract

Abstract. A new and extensive system of glaciovolcanic caves has developed around the 2004–2008 lava dome in the crater of Mount St. Helens, Washington, USA. These systems offer a rare view into a subglacial environment and lead to a better understanding of how glaciers and active volcanoes interact. Here, we present first results from geodetic and optical surveys done between 2014 and 2019 as well as climatologic studies performed between 2017 and 2019. Our data show that volcanic activity has altered subglacial morphology in numerous ways and formed new cave systems that are strongly affected by heat flux from several subglacial fumaroles. More than 2.3 km of cave passages now form a circumferential pattern around the dome, some several hundred meters long. Air and fumarole temperature measurements were conducted in two specific caves. Whereas air temperatures reveal a strong seasonal dependency, fumarole temperatures are affected to a minor extent and are primarily regulated by changes in volcanic heat flux or the contribution of glacial melt. Related studies from Mount Hood, Oregon, and Mount Rainier, Washington, are used as comparison between glaciovolcanic cave systems. Fumarolic heat and resulting microclimates enable further genesis of this dynamic system. Already one of the largest worldwide, it is very likely that the system will continue to expand. As Mount St. Helens is the Cascade Volcano most likely to erupt again in the near future, these caves represent a unique laboratory to understand glaciovolcanic interactions, monitor indicators of recurring volcanic activity and to predict related hazards.

Glacial environments can have significant impacts on the surrounding landscape and nearby populations when affected by volcanic activity. As such, glaciovolcanic interactions and related hazards have received substantial attention during the last few decades. In contrast, the study of void spaces created by these interactions—glaciovolcanic cave systems—remains underrepresented. This review outlines the global distribution of glaciovolcanic caves and describes examples of both historical and ongoing research advances, most of which are limited to volcanoes of the Cascade Volcanic Arc and Antarctica. Examples range from a largely static fumarolic ice cave system in the crater of Mount Rainier to glaciovolcanic cave genesis and evolution in the crater of Mount St. Helens, where the advancing glacier ice is interacting with ongoing fumarolic activity and generating new cave systems. This review includes various volcanic subfields and also brings together additional disciplines including speleology, microbiology, and astrobiology. Due to the importance of glaciovolcanic caves in the hydrothermal cycle of volcanic systems, the global fight against antibiotic resistance, and their implications for understanding volcano-ice interactions beyond Earth, research on these systems is expanding. Kamchatka, Alaska, and Iceland have notable potential for further studies, while known research sites still hold open questions, including better understanding of the environmental parameters affecting cave genesis and persistence, the effect of glaciovolcanic cave development on underlying hydrothermal systems, and cataloging the biodiversity of glaciovolcanic cave environments.

No abstract