The term “ice volcano” is applied to two distinct natural phenomena that share a conical shape and an eruptive process. These formations are found both on Earth’s frozen lakes and across the distant, icy bodies of the outer solar system. Although they look similar, the forces that create these structures are vastly different, ranging from wind and wave action to the immense gravitational tug of giant planets.
Defining the Two Types of Ice Volcanoes
The unifying characteristic of an ice volcano is a conical mound of ice with a central vent, but their origins separate them into two distinct categories. The first type is the terrestrial ice cone, a transient feature formed on the surfaces of large, frozen lakes, such as the Great Lakes in North America. These Earth-based structures are purely surface phenomena, driven by external environmental forces, and are made almost entirely of frozen lake water and slush.
The second type is the extraterrestrial cryovolcano, a feature observed on icy moons and dwarf planets. These are true volcanic structures that erupt volatile liquids and gases instead of molten rock. The erupted material is often referred to as cryomagma or cryolava, a mixture that can include liquid water, ammonia, methane, and hydrocarbons.
Mechanism of Terrestrial Ice Cone Formation
Terrestrial ice cones are formed by a combination of high winds, open water, and near-freezing temperatures. The process begins when strong winds blow onshore, generating waves that crash against the edge of a stable ice shelf near the lake’s coast. This wave action creates a small channel or fissure in the ice shelf.
As the waves continue to break, water and slush are forcibly ejected upward through this opening. The spray immediately freezes upon contact with the frigid air, falling back down around the vent. This continuous cycle of eruption and refreezing gradually builds up a conical mound of ice.
The resulting cone can range from less than one meter up to ten meters, influenced by wind velocity and the amount of open water available for wave generation. These formations are temporary structures, frequently destroyed by storms or warmer weather. The eruptions cease entirely once the entire lake surface freezes solid.
Extraterrestrial Cryovolcanism
Cryovolcanism on distant celestial bodies is driven by internal heat sources that melt or mobilize the icy subsurface material, known as cryomagma. Unlike Earth’s volcanoes, cryovolcanoes erupt a liquid blend of water and other volatile compounds, such as ammonia and methane, which have a much lower freezing point than silicate magma. This cold, pressurized subsurface liquid rises through the icy crust to the surface, where it rapidly freezes in the vacuum of space, constructing volcanic landforms.
The primary source of heat for many of these icy worlds is tidal flexing, the gravitational squeezing and stretching caused by orbiting a giant planet like Saturn or Jupiter. This gravitational friction generates enough heat to keep a layer of liquid or partially melted material beneath the outer ice shell. For example, on Saturn’s moon Enceladus, the Cassini mission confirmed active plumes of water ice and vapor erupting from fractures near the south pole.
Other icy bodies, such as the dwarf planet Ceres, may rely on radiogenic heat from the decay of radioactive elements within their rocky core to power the process. The erupted material, called cryolava, can form large-scale features like the proposed mountain Ahuna Mons on Ceres, or the vast, resurfaced plains observed on Neptune’s moon Triton. The study of these cold eruptions provides insights into the potential for subsurface oceans.