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A phreatic eruption (Mount St. Helens, 1980)


From Ancient Greek stem of φρέαρ (phréar, well, spring).

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phreatic (comparative more phreatic, superlative most phreatic)

  1. (geology) Of or pertaining to ground water; (volcanology) involving explosively rapid heating of ground water by magma.
    • 1979 [McGraw-Hill], Jacob Bear, Hydraulics of Groundwater, 2007, Dover, page 76,
      Both and q vary from point to point within a phreatic aquifer.
    • 1981, Peter W. Lipman, James G. Moore, Donald A. Swanson, Bulging of the North Flank Before the May 18 Eruption—Geodetic Data, Peter W. Lipman, Donal R. Mullineaux (editors), The 1980 Eruptions of Mount St. Helens, Washington, U.S. Geological Survey, page 143,
      These results contributed to assessments by USGS personnel in late April and early May that Mount St. Helens remained highly dangerous despite the seemingly mild small-scale phreatic eruptions that were then the most conspicuous activity.
    • 1992, Angel Ginés, Joaquin Ginés, Karst Phenomena and Biospeleological Environments, Ana Isabel Camacho (editor), The Natural History of Biospeleology, Consejo Superior de Investigaciones Cientificas, page 43,
      Gradually, infiltrating waters gather in underground rivers or phreatic conduits well integrated in the karst drainage system, which leads the underground waters to the outlets.
    • 2010, Jose Collazo, God Does Exist, No More Nuclear Testing and More, Xlibris, page 58,
      Phreatic” (or steam-blast) eruptions are driven by explosive expanding steam resulting from cold ground or surface water coming into contact with hot rock or magma. The distinguishing feature of phreatic explosions is that they only blast out fragments of preexisting solid rock from the volcanic conduit; no new magma is erupted.

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