Phreatic eruption at the summit of Mount St. Helens, Washington.

Phreatic eruptions occur when rising magma makes contact with ground or surface water. The extreme temperature of the magma (anywhere from 600°C to 1,170°C) causes near-instantaneous evaporation to steam resulting in an explosion of steam, water, ash, rock, and volcanic bombs. At Mount St. Helens hundreds of steam explosions preceded a 1980 plinian eruption of the volcano. A less intense geothermal event may result in a mud volcano. Phreatic eruption at the summit of Mount St. ... Phreatic eruption at the summit of Mount St. ... This article is about the type of molten rock. ... Groundwater is any water found below the land surface. ... In physical chemistry and in engineering, steam refers to vaporized water. ... Volcanic bombs are globules of melted rock (tephra) larger than 2. ... Mount St. ... Eruption of Vesuvius in 1822. ... A volcano is a geological landform (usually a mountain) where magma (rock of the Earths interior made molten or liquid by extremely high temperatures along with a reduction in pressure and/or the introduction of water or other volatiles) erupts through the surface of the planet. ... The term mud volcano or mud dome is used to refer to formations created by geologically excreted liquids and gases, although there are several different processes which may cause such activity. ...

Phreatic eruptions typically include steam and rock fragments; the inclusion of lava is unusual. If molten material is included, the term phreato-magmatic may be used. These eruptions occasionally create broad, low-relief craters called maar. Phreatic explosions can be accompanied by carbon dioxide and or hydrogen sulfide gas emissions; both gases are deadly. A 1979 phreatic eruption on the island of Java killed 149 people, most of whom were overcome by poisonous gases. The word crater may refer to A landform resembling a pit or depression in the topography that can be formed in several ways: a meteorite impact with another body can cause an impact crater, an electrical discharge such as lightning may form a crater-like pit, volcanic activity may form... This page describes the geological feature. ... Carbon dioxide is an atmospheric gas composed of one carbon and two oxygen atoms. ... Hydrogen sulfide (hydrogen sulphide in British English), H2S, is a colorless, toxic, flammable gas that is responsible for the foul odor of rotten eggs. ... Map of Java Java (Indonesian, Javanese, and Sundanese: Jawa) is an island of Indonesia, and the site of its capital city, Jakarta. ...

It is believed the 1883 eruption of Krakatoa - which obliterated most of the volcanic island and created the loudest sound in recorded human history - was a phreatic event. Kilauea, in Hawaii, has a long record of phreatic explosions; a 1924 phreatic eruption hurled rocks estimated at eight tons up to a distance of one kilometer. 1883 was a common year starting on Monday (see link for calendar). ... Krakatoa (Indonesian name: Krakatau) is a volcano near the Indonesian island of Rakata in the Sunda Strait. ... KÄ«lauea is an active volcano in the Hawaiian Islands, one of seven shield volcanos that together form the Island of Hawai‘i. ... State nickname: The Aloha State Other U.S. States Capital Honolulu Largest city Honolulu Governor Linda Lingle (R) Senators Daniel Inouye (D) Daniel Akaka (D) Official languages Hawaiian and English Area 28,337 km² (43rd)  - Land 16,649 km²  - Water 11,672 km² (41. ... 1924 was a leap year starting on Tuesday (link will take you to calendar). ...

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USGS Photo Glossary Entry for "Phreatic Eruption"