Phreatic eruption

[2] At Mount St. Helens in Washington state, hundreds of steam explosions preceded the 1980 Plinian eruption of the volcano.

[citation needed] Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual.

If molten magma is included, volcanologists classify the event as a phreatomagmatic eruption.

Carbon dioxide can asphyxiate at sufficient concentration; hydrogen sulfide acts as a broad-spectrum poison.

A 1979 phreatic eruption on the island of Java killed 140 people, most of whom were overcome by poisonous gases.

A scheme of a phreatic eruption: 1: water-vapor cloud, 2: magma conduit, 3: layers of lava and ash, 4: stratum, 5: water table, 6: explosion, 7: magma chamber
Phreatic eruption at the summit of Mount St. Helens , Washington, in the spring of 1980