subglacial volcanism

Subglacial volcanism occurs when volcanoes erupt beneath glaciers or ice sheets. This interaction between magma and ice can lead to dramatic geological formations and events.

When magma erupts under ice, the rapid vaporization of ice can build up immense gas pressure. This pressure can result in explosive eruptions of steam and ash. A notable example is Iceland's Katla volcano, a subglacial volcano that has produced explosive eruptions when its rising magma contacts the overlying ice. These eruptions can generate large ash clouds and significant lahars (volcanic mudflows) due to the melted glacier ice.

The resulting landforms from subglacial volcanism can differ significantly from those formed by eruptions in ice-free environments. For instance, repeated eruptions from point-source vents under ice can create table mountains with steep sides made of pillow lavas, capped by fragmented lava from shallow-water eruptions.1