Melting Antarctic ice sheets may be causing larger volcanic eruptions
Melting ice sheets are often considered synonymous with climate change in the media, with evocative images of lone polar bears floating on ever-shrinking rafts of ice. While impacts such as sea level rise and salinity changes ...
During deglaciation, melting of kilometers-thick ice sheets reduces the mass weighing down the land, which leads to uplift. This alters the pressure inside magma chambers lying below the Earth's surface, causing volcanic eruptions.
Research, published in Geochemistry, Geophysics, Geosystems, suggests that mass unloading due to melting of Antarctic ice sheets (isostatic rebound) is triggering eruptions of greater frequency and magnitude in the West Antarctic Rift System, one of Earth's largest volcanic provinces with over 100 eruptive centers.
Ph.D. researcher Allie Coonin, of Brown University, and colleagues investigated the interaction of glaciation and volcanism over the last two planetary glacial cycles (within the last 150,000 years).
To do so, they used a thermomechanical magma chamber model and simulated a shrinking West Antarctic Ice Sheet through inputting specific pressure decreases exerted on the underlying rocks and magma chamber.
They further explored how the reduction of this confining pressure allows the magma chamber to expand volumetrically, with associated overpressurization and expulsion of volatiles (here when dissolved water and carbon dioxide form gas bubbles) from basalt magmas affecting the trajectory of future eruptions.
Schematic of the thermomechanical magma chamber model with simulated ice unloading from this study. Transparent arrows represent ice unloading as a decrease in the ice layer thickness over time. Credit: Geochemistry, Geophysics, Geosystems (2024). DOI: 10.1029/2024GC011743
Results of modeled pressure changes in magma chamber in response to different rates of ice mass unloading and the equivalent mass of erupted magma over 3,000 years. Credit: Coonin et al., 2024.
Records of cumulative volume erupted from three volcanoes in the Andean Southern Volcanic Zone, corresponding to glacial cycles over the last 150,000 years. Credit: Coonin et al., 2024.