Geyser

Geyser
Geothermal spring
Strokkur geyser, Iceland
Formed by	Particular hydrogeological conditions that exist in a few places on Earth

A geyser (/ˈɡaɪzər/, UK: /ˈɡiːzər/)^[1][2] is a spring with an intermittent discharge of water ejected turbulently and accompanied by steam. The formation of geysers is fairly rare, and is caused by particular hydrogeological conditions that exist only in a few places on Earth.

Generally, geyser field sites are located near active volcanic areas, and the geyser effect is due to the proximity of magma. Surface water works its way down to an average depth of around 2,000 metres (6,600 ft) where it contacts hot rocks. The pressurized water boils, and this causes the geyser effect of hot water and steam spraying out of the geyser's surface vent.

A geyser's eruptive activity may change or cease due to ongoing mineral deposition within the geyser plumbing, exchange of functions with nearby hot springs, earthquake influences, and human intervention.^[3] Like many other natural phenomena, geysers are not unique to Earth. Jet-like eruptions, often referred to as cryogeysers, have been observed on several of the moons of the outer Solar System. Due to the low ambient pressures, these eruptions consist of vapour without liquid; they are made more easily visible by particles of dust and ice carried aloft by the gas. Water vapour jets have been observed near the south pole of Saturn's moon Enceladus, while nitrogen eruptions have been observed on Neptune's moon Triton. There are also signs of carbon dioxide eruptions from the southern polar ice cap of Mars.

In the case of Enceladus, the plumes are believed to be driven by internal energy. In the cases of the venting on Mars and Triton, the activity may be a result of solar heating via a solid-state greenhouse effect. In all three cases, there is no evidence of the subsurface hydrological system which differentiates terrestrial geysers from other sorts of venting, such as fumaroles.