It is believed that there are about 1,000 natural geysers on Earth, with most of them concentrated in three so-called "geyser fields": Yellowstone National Park in Wyoming (USA), the Valley of Geysers in Kamchatka, and the El Tatio geothermal field on the Altiplano plateau (Chile) (Bryan, 1995). The Valley of Geysers is considered as the second largest field in the world after Yellowstone in terms of the number of geysers. There are also isolated geysers that are randomly scattered across many volcanic regions of the world. Total number of geysers is very hard to estimate such as they are very diverse and short-lived. They can cease activity both for natural reasons and as a result of human activity during the exploitation of the geothermal energy of the area, or, conversely, new geysers are formed. Methods for geyser’s counting are also not agreed upon (Belousov and Belousova, 2024).

The Valley of Geysers was discovered in the central part of Kamchatka in 1941 by Tatyana Ustinova. This geyser field became the last large geyser field discovered on Earth (Ustinova, 1955; Naboko, 1954). At present, in Russia, in addition to the geysers of the Valley of Geysers, two more active geysers are known - also in Central Kamchatka: one in the Uzon caldera and one on the shore of the Karymskoye Lake. Also there is evidence of the existence at Kamchatka in the past some single geysers: at Uzon (Droznin, 2009), Karymskoye Lake, Pauzhetka, as well as at Shiashkotan Island (Kuriles).

Geyser is a spring that periodically throws a steam-water mixture to the surface (Nekhoroshev, 1959). From this definition it follows that the main feature of a geyser is its intermittent activity: the emission of water and steam is interrupted by stages of rest, when nothing comes to the surface of the earth, but a gradual filling of the geyser's supply system, emptied during the previous eruption, occurs. Thus, a constantly active hydrothermal source is not a geyser.

The geyser regime is a sequential change in the stages of its activity (Sugrobov et al., 2009):

• eruption (outpouring of water, fountaining of a steam-water mixture, steaming);
• complete rest (restoration of the level of hot water in the channel).

Periodicity is the main feature of each geyser. It is the duration of its activity from any stage to its repetition, for example, between the stages of fountaining. Usually it is within the range from several minutes to several hours. The frequency of geysers activity can change over time because of hydrometeorological situation, earthquakes or changes in the morphology of the relief at the place of discharge of thermal waters (Sugrobova, 1982).

Dwarf geyser is a geyser whose eruption height is several centimeters, the duration of the eruption is several seconds, and the frequency is several minutes.

Boiling pulsating spring is a hot spring in which the water flow rate changes and there is no resting stage.

The presence of a resting stage distinguishes a geyser from other pulsating (including boiling) springs. The operating mode of a geyser can change over time - a geyser can "turn" into a pulsating source, and vice versa (Leonov, 2017).

References

Belousov A.B., Belousova M.G. (2024) Geysers - geothermal sources by which you can set your watch // Priroda, No. 9. P. 3-15
Bryan T. Scott. The geysers of Yellowstone. United States, University Press of Colorado, 1995. 463 p.
Droznin V.A. (2009) New geyser in the caldera of Uzon volcano // Bulletin of KRAUNC. Series: Earth Sciences. Issue 14. No. 2. P. 10-12.
Leonov A.V. (2017) Catalog of geysers of the Kronotsky Nature Reserve. Valley of Geysers and Caldera of Uzon Volcano: History and Modernity. 384 p.
Nekhoroshev A.S. (1959) On the Theory of Geyser Action // Reports of the USSR Academy of Sciences. No. 127(5). P. 1096-1098.
Naboko S.I. (1954) Geysers of Kamchatka // Transactions of the Laboratory of Volcanology of the USSR Academy of Sciences. No. 8. Pp. 126-209.
Sugrobov V.M., Sugrobova N.G., Droznin V.A., Karpov G.A., Leonov V.L. (2009) The Pearl of Kamchatka - the Valley of Geysers. Science guide, 108 p.
Sugrobova N.G. (1982) Some regularities of the geyser regime of Kamchatka // Volcanology and Seismology. Issue. 5. Pp. 35-48.
Ustinova T.I. (1955) Kamchatka geysers. 119 p.