phreatic


Also found in: Dictionary, Wikipedia.
Related to phreatic: phreatic water, Phreatic zone

phreatic

[frē′ad·ik]
(geology)
Of a volcanic explosion of material such as steam or mud, not being incandescent.
References in periodicals archive ?
Pilots are advised to avoid flying close to the volcano's summit as ash from phreatic eruptions could harm aircraft.
It warned pilots to avoid flying close to the volcano's summit, as ash from any sudden phreatic eruption can be hazardous to aircraft.
Civil aviation authorities were asked to advise pilots to avoid flying close to the volcano's summit as sudden phreatic explosions can be hazardous to aircrafts.
'Instability will arise in either case if sufficient consideration is not paid to seepage and the position of the phreatic surface,' he says.
A phreatic explosion reportedly occurs when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits.
"Oftentimes these phreatic systems are triggered by processes going on in the magma, which are then triggering processes going on in the hydrothermal system, which then erupt," he said.
Phreatic eruption 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.
Almost 17,500 people living within Mayon's six-to-seven-kilometer danger zone have been evacuated since the volcano started to spew steam and ash clouds during a phreatic eruption - a steam-driven explosion - on Saturday.
where [h.sub.phreatic] is the waterhead within the influence radius of dewatering in phreatic water layer; [h.sub.w] is the water level in the well; [H.sub.0] is the aquifer thickness; r is the distance between the measuring point and the center of the dewatering well; R is the influence radius of the dewatering.
** Elevation of the water table (phreatic surface); and