According to the National Park Service,
“Geysers are hot springs with constrictions in their
plumbing, usually near the surface, that prevent water
from circulating freely to the surface where heat would
escape” (“Nat’l Park Service”). Geysers are not very
common and only form under certain conditions where there
is volcanic heat and water. The process by which a geyser
erupts can be explained relatively simply. Water
flows into an underground pocket that is close to magma by
either leaching through from the Earths surface or from an
underground reservoir. The nearby magma causes the rocks
that surround this chamber to be very hot and in turn they
begin heating the water. Due to the underground conditions,
the water is heated to a temperature above what it would
normally boil at on the Earth's surface, and a great deal of
pressure is created (this will be discussed later in more
detail). As the pressure continues to build, the water
finally begins to boil, and all of a sudden the combination
of pressure and steam cause all of the liquid and gas water
to be expelled out of the surface of the Earth- sometimes
shooting hundreds of feet into the air!
earthsystems/plate_tectonics/pop_geyser.html
