A geyser is a type of hot spring which emits water and steam, sometimes accompanied by other gases, in the form of intermittent rashes. For their formation it is necessary that some hydrogeological characteristics concur that only occur in a few regions of our planet, which makes geysers a rare phenomenon.

The number of active geysers annually is around 1,000 worldwide. However, geysers are not exclusive to Earth, it is likely that they exist on other planets, for example on Mars or on Europa, one of the Galilean satellites of Jupiter. In these systems, geysers are often known as cryogysers or cryovolcanoesas they emit various volatile substances along with dust and ice particles at low temperatures.

working of a geyser

Geysers occur in volcanically active areas where there is magma chambers relatively close to the surface. Through cracks and fractures in the rocks, the water filters and can reach great depths, even beyond 2 km.

When water comes into contact with rocks heated by magma, it begins to boil. increased pressure in the system until there comes a time when the hot water and steam is ejected eruptively and gives rise to geysers. This phenomenon is also known as hydrothermal explosion.

Geysers can be explained as a system of pipes that transports heated water deep within the earth’s crust. These “pipes” would be formed by cracks associated with faults and volcanic zones. In many geysers, deep cavities are formed where steam and superheated water accumulate, gradually increasing the pressure.

The high pressure that is reached in the depths increases the boiling point of the water, which allows it to be heated. above 100ºC and keep it liquid. This very hot water under high pressure pushes the water from the upper conduits until the geyser explodes.

The interval between eruptions is highly variable from one geyser to another. For example, the geyser Strokkur (Iceland), has short eruptions every few minutes, while the geyser Grand Geyser (United States) has eruptions every 8-12 hours and each eruption can last up to 10 minutes continuously.

Depending on the exact operation and characteristics of the eruptions, geysers are usually classified into two main types:

  1. fountain geyser: The eruptions occur in the form of intense explosions in surface water pools. For example, the Fountain Geyser, in Yellowstone (United States).
  2. cone geyser: the eruption occurs through a small crater on a cone of siliceous rock, generally geyserite. Eruptions are usually in the form of jets, less violent and longer lasting than in fountain geysers. For example, the Old Faithful, also in Yellowstone.

Why are they so rare?

There are many volcanic areas with hydrothermal vents, fumaroles, and similar formations that involve the expulsion of hot water and steam, but very few that erupt in the form of geysers. Many of the conditions for geysers to form are quite common, but they all have to occur at the same time for the water to reach the surface at high pressure.

For example, if the rocky structure through which the pressurized hot water circulates is not strong enough, the channel system is quickly destroyed without giving time for a possible nascent geyser to form.

This is why most geysers appear in areas of volcanic activity with presence of rhyolitean extrusive igneous rock that dissolves in hot water and precipitates as siliceous minerals, mostly geyseritea very abundant mineral in geysers that coats the walls of the channels and hardens them allowing the geysers to persist.

In short, a geyser is a fragile phenomenon that requires very precise conditions to exist. If these conditions change, the geyser can shut down or go dormant, and many times the geyser shutdown is induced by human activity. For example, there are geysers turned off due to the accumulation of human waste or due to a lack of water to feed the system after the installation of geothermal plants in the vicinity.