The term phreatic is used in geology to refer to matters relating to underground water below the water table (the word originates from the Greekphrear, phreat- meaning "well" or "spring"). The phreatic zone is the layer(s) of soil or rock below the water table in which voids are permanently saturated with water, as opposed to the higher vadose zone in which the pore spaces are not completely filled with water. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... The water table is the upper limit of abundant groundwater. ... The Greek language (Greek Ελληνικά, IPA – Hellenic) is an Indo-European language with a documented history of some 3,000 years. ...
Certain types of extremely violent volcanic eruptions can result from the interaction of ground water and magma; these are termed phreatic eruptions. This article is about volcanoes in geology. ... This article is about the type of rock. ... Categories: Geology stubs | Volcanoes ...
Phreatic eruptions are steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits (for example, tephra and pyroclastic-flow deposits).
The intense heat of such material (as high as 1,170° C for basaltic lava) may cause water to boil and flash to steam, thereby generating an explosion of steam, water, ash, blocks, and bombs.
Phreatic eruption at the summit of Mount St. Helens, Washington.
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