Phreatic eruption

Phreatic eruptions typically include steam and rock fragments; the inclusion of liquid lava is unusual. The temperature of the fragments can range from cold to incandescent. If molten magma is included, volcanologists classify the event as a phreatomagmatic eruption. These eruptions occasionally create broad, low-relief craters called maars. Phreatic explosions can be accompanied by carbon dioxide or hydrogen sulfide gas-emissions. 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.

Examples of phreatic eruptions

• Cumbre Vieja – In the 2021 La Palma eruption, new eruptive vents tended to announce themselves with a phreatic explosion, followed soon after by the opening of a new fissure vent in the same location.
• Krakatoa – Indonesia, 1883 (see 1883 eruption of Krakatoa) – it is believed that the eruption, which obliterated most of the volcanic island and created the loudest sound in recorded history, was a phreatomagmatic event.
• Ritter Island – Papua New Guinea, 1888 (see 1888 Ritter Island eruption and tsunami) – Resulted in the largest lateral spreading of a volcanic cone in human history.
• Kilauea – Hawaii, United States – the volcano has a long record of phreatic explosions; a 1924 phreatic eruption hurled rocks estimated at eight tons up to a distance of one kilometer.
• Surtsey – Iceland, 1963–65
• Taal Volcano – Philippines, 1965, 1977, 2020
• Mount Ontake – Japan, 2014 (see 2014 Mount Ontake eruption)
• Mayon Volcano – Philippines, 2013
• Whakaari/White Island – New Zealand, 2019 (see 2019 Whakaari/White Island eruption)
• Mount Bulusan – Philippines, 2022