Antarctica is a geologically active landmass, despite being largely covered by a massive ice sheet. While much of the volcanic activity is hidden beneath the ice, the presence of these structures confirms that the Earth’s crust underneath the southernmost continent is not static. Antarctica’s tectonic setting, characterized by significant crustal stretching, creates conditions conducive to magma formation and ascent. The existence of these volcanoes gives scientists a window into the dynamic processes occurring deep beneath the ice and rock.
The Distribution of Antarctic Volcanoes
The vast majority of Antarctica’s known volcanic structures are concentrated in West Antarctica. This concentration is directly related to the presence of the West Antarctic Rift System, a major tectonic boundary where the continental crust is actively thinning and pulling apart. This geological process allows magma from the mantle to rise closer to the surface, fueling the volcanic field.
East Antarctica, in contrast, is an ancient, stable craton, which explains the relative lack of volcanic activity in that region. Scientists have identified a substantial number of these structures, with some studies suggesting a total inventory of nearly 140 volcanic cones and mountains in the West Antarctic region alone. A 2017 study, for example, newly identified 91 potential volcanoes hidden beneath the ice sheet. The volcanoes found in Antarctica exhibit a variety of forms, including large stratovolcanoes and broader shield volcanoes. Many of the newly discovered subglacial structures are thought to be cones composed of basaltic rock, a type of lava commonly associated with rift zone volcanism.
Active, Dormant, and Extinct Classifications
Volcanoes are generally categorized based on their current and potential eruptive status. An active volcano is one that is currently erupting or shows consistent signs of unrest, while a dormant volcano is quiet but capable of erupting again. An extinct volcano is considered highly unlikely to erupt in the future.
The most prominent example of an active Antarctic volcano is Mount Erebus, located on Ross Island. It is the world’s southernmost historically active volcano and has been in a state of continuous eruption since at least 1972. Mount Erebus is famous for hosting one of the few persistent, convecting lava lakes on Earth, where molten rock circulates within its summit crater. This constant activity provides scientists with a rare opportunity to study a polar volcanic system.
Scientists monitor this activity using satellite data to detect thermal anomalies and gas emissions, as well as on-site seismometers to track magma movement. Dormant peaks, such as Mount Sidley—the continent’s tallest volcano—are known to have erupted in the past but currently show no signs of activity. The difficulty in confirming the status of many of the subglacial volcanoes means their classification often remains uncertain, relying on interpretations of their shape and surrounding geological evidence.
Subglacial Volcanism and Ice Sheet Dynamics
Many of Antarctica’s volcanoes are completely buried beneath the massive ice sheet, leading to the phenomenon known as subglacial volcanism. These hidden structures are detected using sophisticated techniques, primarily airborne ice-penetrating radar and seismic mapping, which allow researchers to visualize the shape of the bedrock beneath the ice. The radar maps reveal conical edifices, which are strong evidence of underlying volcanoes.
The heat generated by these volcanoes, even when not actively erupting, has a direct influence on the base of the ice sheet. Geothermal heat flow melts the basal ice, creating vast networks of subglacial lakes and contributing to the formation of water pathways. This meltwater acts as a lubricant, which can significantly influence the speed and movement of ice streams toward the ocean. The continuous, low-level heat from these subglacial systems is a persistent factor in ice dynamics. The stability of the West Antarctic Ice Sheet is potentially linked to the geothermal environment, as the ongoing heat contributes to basal lubrication and can influence the rate of ice loss.