Look up phreatic in Wiktionary, the free dictionary.
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 chamberPhreatic eruption at the summit ofMount St. Helens, Washington, in the spring of 1980
Phreatic eruptions typically include steam and rock fragments; the inclusion of liquidlava is unusual. The temperature of the fragments can range from cold toincandescent. If molten magma is included, volcanologists classify the event as aphreatomagmatic eruption. These eruptions occasionally create broad, low-relief craters calledmaars. Phreatic explosions can be accompanied bycarbon dioxide orhydrogen sulfide gas-emissions. Carbon dioxide canasphyxiate at sufficient concentration; hydrogen sulfide acts as a broad-spectrum poison. A 1979 phreatic eruption on the island ofJava killed 140 people, most of whom were overcome by poisonous gases.[3]
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.[7]
^"On February 20th, 1979, 142 inhabitants of Dieng Plateau (Indonesia) were asphyxiated by poisonous gases during a mild phreatic eruption. From later fields gas collection and analysis, the casualties are considered to be due to CO2 rich volcanic gases." F. Le Guern, H. Tazieff and R. Faivre Pierret, "An example of health hazard: People killed by gas during a phreatic eruption: Diëng plateau (Java, Indonesia), February 20th 1979",Bulletin of Volcanology45 (1982): 153–156.
^"A precursory phreatic or phreatomagmatic stage has been identified in the 1883 Krakatau eruption (Simkin and Fiske, 1983)". A precursory phreatic or phreatomagmatic stage has been identified in the 1883 Krakatau eruption (Simkin and Fiske, 1983). David J. W. Piper, Georgia Pe-Piper and Darren Lefort, "Precursory activity of the 161 ka Kos Plateau Tuff eruption, Aegean Sea (Greece)",Bulletin of Volcanology72 (2010): 657–669.
^Simkin T, Fiske RS (1983)Krakatau 1883: The Volcanic Eruption and its Effects.Smithsonian Institution Press, Washington.
^"On May 10, 1924, a violent phreatic (steam) eruption began in Halema'uma'u that sent repeated columns of ash high into the sky. The explosions continued for 18 days, with the largest occurring on May 18. The steam explosions hurled rocks as large as eight tons as far as 0.6 miles from the crater; these blocks still surround Halema'uma'u. One of these blocks fatally injured a Mr. Taylor, who approached too close to the crater to take a photograph."Phreatic Eruptions, Hawaiian Volcano Observatory,US Geological Survey, 6 May 1994.
