A geyser is a particular type of sources of warm water which spouts out intermittently by projecting Eau at high temperature and vapor. The geyser term comes from Geysir , the name of the most famous geyser Icelandic, whose etymology is related to the verb Icelandic gjósa (in French to spout out ).

Description

The activity of the geysers, like that of all the hot sources, is related to an in-depth water infiltration. Water is heated by its meeting with a rock, it even heated by the magma in fusion or by the action of the geothermic gradient (the temperature and the pressure increase with the depth), this is why it is possible to find sources of warm water and geysers in the nonvolcanic areas. This water, heated and pressurized, flashes back then towards surface by effect of convection. The geysers differ from the simple hot sources by the underground geological structure. The opening of surface generally narrow, is connected to fine conduits which lead to imposing underground water tanks.

The intensity of the forces concerned explains the scarcity of the phenomenon. Around many volcanic zones, one can find hot sources accompanied by fumerolles (island St Lucia, Java, Dallol, etc). But often, the rocks are too friable, which generates a fast erosion and condemns the appearance of a geyser which must have narrow and resistant natural conduits.

The activity of a geyser is rather fragile and capricious and certain died out because waste there had been simply thrown. The other reason is of course the exploitation of geothermal energy. Indeed, certain geysers are not active any more following the human intervention, in particular after the construction of geothermic power stations .

One should not confuse a geyser with others phenomena paravolcanic:

• a Fumerolle is a crack releasing of the sulfurous plumes of smoke and the steam

• a hot source is a thermal basin, energy of 30° with 100°, or a very hot geothermic lake (like the Prismatic Spring for example);

• a Mare of mud is a small bubbling water lake brewing sediments on its surface (volcanic mud, clay, materials… etc);

• a Mofette is a warm water well with increase of sometimes toxic gas bubbles.

Eruptive cycle

The first phase of an eruptive cycle of a geyser is the filling of the water column. The temperature of this water decreases then at the top of the column what is not the case of that of the tank because of the narrowness of the conduit. The Pression of water in the bottom of the column is such as it makes it possible water not to enter in boiling beyond 100 °C.

When the Densité of the water overheated in the bottom of the column cannot overcome the pressure any more, this layer of warm water starts to go up in the conduit. The pressure and the temperature decreasing, the increase accelerates all the more quickly as the first gas bubbles are formed. Water present on the surface of the water column is then pushed out of the conduit forming a water mass running out on with dimensions ones of the conduit.

The bubbles of gas frays to the warm water column bores surface then and spouts out in a jet which can reach several meters height. Once the expelled warm water and the pressure fallen down, a new eruptive cycle begins again with the filling of the water column.

Types of geyser

There exist two types of geysers. The geyser known as “fountain” is finished by a narrow cone, with a very fine conduit. When an eruption occurs and that a water column spouts out, it in fact is expelled by the pressure due to the narrowness of the conduit. It is the case for example of Old Faithful.

The other type of geyser is the geyser known as “gas” . It is generally about an hot source which, when gas is expelled, makes go up the water bubbles which explode in contact with surface and which create a broad water column, often of short duration. It is the case for example of Strokkur.

Eruptive sequence of a geyser in image

Geographical distribution

The geysers are relatively rather rare because dependant on climatic conditions and geological which one finds only in few places on ground. There all over the world exist five principal zones of geysers and six other secondary zones with less geysers :

• the National park of Yellowstone located in the Wyoming (the United States) concentrates two thirds of the geysers existing in the world;
• the Iceland;
• the peninsula of the Kamtchatka in Russia (Vallée of the geysers celebrates it was completely destroyed following the slip of the ground which has occurred the May 4th 2007);
• the Geysers del Tatio with the Chile;
• the island of North in New Zealand;
• the crater of the Volcano Dallol in Ethiopia;
• the volcano of the Sulfur mine to St Lucia;
• At the bottom of the crater of the volcano Mahawu, in Sulawesi
• There was with the Nevada, unfortunately extinct because of thermal industry, but there exists one with the Utah, the Fly geyser;
• with the Peru;
• in Bolivia;
• in Argentinian (Copahue);
• in Alaska (the United States): Umnak island;
• with the the Azores;
• with the Kenya, in the Lake Bogoria;
• with the Japan.

Some examples of geysers in the world:

Yellowstone is by far the most active zone in the world with nearly 400 listed geysers. The park has moreover the two most imposing specimens whose Old Faithfull celebrates it.

Dallol is famous for its molten salt and sulfur concretions. Small gas geysers appear in the site

With the Sweet flags, it is especially about very hot water mixed with molten Oxide iron.

In Kenya, it is with the lake Bogoria, located in the same volcanic axis as the famous Lac Turkana, than one can find tens of bubbling hot sources and the geysers, gas and in cones.

In St Lucia, one finds in particular fumerolles and ponds of muds. Small geysers are also present but do not exceed the 50 centimetres.

Random links:

Jean Falconer | Weddings of blood (film) | Brad Arnold | Ejisu-Juaben | Channel of Tancarville