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What is a Geyser?

What is a Geyser?

A geyser is a vent in Earth's surface that periodically ejects a column of hot water and steam. Even a small geyser is an amazing phenomenon; however some geysers have eruptions that blast thousands of gallons of boiling hot water up to a few hundred feet in the air.

Old Faithful is the world's best known geyser. It is located in Yellowstone National Park (USA). Old Faithful erupts every 60 to 90 minutes and blasts a few thousand gallons of boiling hot water between 100 and 200 feet into the air.

Related:   The World's Tallest Geyser

Conditions Required for a Geyser

Geysers are extremely rare features. They occur only where there is a coincidence of unusual conditions. Worldwide there are only about 1000 geysers and most of those are located in Yellowstone National Park (USA).

Conditions Required for Geysers
1) hot rocks below
2) an ample groundwater source
3) a subsurface water reservoir
4) fissures to deliver water to the surface

Where are Geysers Found?

Most of the world's geysers occur in just five countries: 1) the United States, 2) Russia, 3) Chile, 4) New Zealand and 5) Iceland. All of these locations are where there is geologically recent volcanic activity and a source of hot rock below.

Geysers in the United States
Umnak Island, Alaska
Kanaga Island, Alaska
Lassen Volcanic National Park, California
Long Valley Caldera, California
Hot Creek and Little Hot Creek, California
Morgan Springs, California
Salton Sea, California (extinct)
Beowawe Geyser Field, Nevada (extinct)
Black Rock Desert, Nevada
Great Boiling Springs, Nevada
Steamboat Springs, Nevada (extinct)
Mickey Hot Springs, Oregon

Countries With Many Active Geysers
1) United States - Yellowstone National Park
2) Russia - Dolina Geiserov
3) Chile - El Tatio
4) New Zealand - Taupo Volcanic Zone
5) Iceland - Many locations

Map of Active Geyser Fields
Map of World Geysers
Map showing the location of world countries with active geyser fields.

YouTube video of Old Faithful Geyser in eruption at Yellowstone National Park. Note how many people are present to witness the eruption!

YouTube video of Iceland's Strokkur Geyser in eruption. Strokkur erupts to heights of up to 70 feet about every 10 to 20 minutes.

How Often Do Geysers Erupt?

Most geysers erupt irregularly and infrequently. However, a few are known for regular eruptions. The most famous, named "Old Faithful" in recognition of its regular eruptions, is located in Yellowstone National Park (USA) and erupts about every 60 to 90 minutes. More details on the eruption intervals of Yellowstone geysers is given in the table below.

Old Faithful is Getting Slower
Research done at the United States Geological Survey suggests that long-term drought conditions in the Yellowstone area have lenghtened the time interval between Old Faithful's eruptions. The delay is thought to be caused by a smaller water supply.

Yellowstone Geysers
Eruption Intervals, Duration, Heights
Location Average Interval Duration Height (ft)
Old Faithful
65 or 92 min
1.5-5 min
5-25 sec
2-4 hours
70 sec
Baby Daisy
35-55 min
3 min
12-18 hours
5 min
5-10 min
12.5 hours
15-20 min
2.5 hours
3.5 min
5-9 hours
6 min
3-5 min
Fan & Mortar
6-10 days?
45 min
5.5 hours
9 min
last eruption 12/24/03
1 hour
last eruption 4/21/04
4-48 hours
8.5 hours
8-12 min
Great Fountain
12.5 hours
45 min
Lion - initial to intitial
about 8 hours
1-7 min
Lion - within series
about 90 min
3-5 min
Little Cub
about 55 min
10 min
3.5-4 min
4 min
recent periods of dormancy
1 min
6.25 hours
20 min
last eruptions 4/27/03, 5/23/05, 7/31/13
10+ min
6.25 hours
20 min
Data from National Park Service
(Measurements done in 2002)

Which Geyser is the World's Largest?

The tallest active geyser in the world is Steamboat Geyser in Yellowstone National Park. Some of its eruptions blast water as high as 400 feet into the air. Don't go to Yellowstone expecting to see it erupt because it has erupted fewer than ten times in the last twenty years.

Waimangu Geyser in New Zealand used to be the tallest geyser in the world. Its eruptions were spectacular, blasting jets of water up to 1600 feet in the air. Unfortunately, a landslide altered the hydrology around Wiamangu and it has not erupted since 1902.

How Do Geysers Work?

To understand how a geyser works, you must first understand the relationship between water and steam. Steam is a gaseous form of water. Steam is produced when water is heated to its boiling point. When water converts into steam at surface conditions it undergoes an enormous expansion because steam occupies 1600 times as much space as the original volume of original water. The eruption of a geyser is powered by a "steam explosion" when boiling hot water suddenly expands into the much more voluminous steam.

To summarize: a geyser erupts when superheated groundwater, confined at depth, becomes hot enough to blast its way to the surface.

Here's what happens in the ground...

Cool groundwater near the surface percolates down into the earth. As it approaches a heat source below, such as a hot magma chamber, it is steadily heated towards its boiling point. However, at the boiling point the water does not convert into steam. This is because it is deep below the ground and the weight of cooler water above produces a high confining pressure. This condition is know as "superheated" - the water is hot enough to become steam - it wants to become steam - but it unable to expand because of the high confining pressure.

At some point the deep water becomes hot enough, or the confining pressure is reduced, and the frustrated water explodes into steam in an enormous expansion of volume. This "steam explosion" blasts the confining water out of the vent as a geyser.

Are There Geysers on Other Planets?

So far, geysers have not been discovered on other planets, however, geyser-like activity has been documented on some of the moons in our solar system. Jupiter's moon, Io, has eruptions of frozen water particles and other gases through vents in its surface. Triton, a moon of Neptune, and Enceladus, a moon of Saturn, also have these cold geysers sometimes called "cryovolcanoes". They are thought to erupt from pools of liquid water located a short distance below the the surface of these moons. On the surface the eruptions are like a "volcanic snow".


Geyser Strokkur - Iceland erupts
A sequence of three photos showing an eruption of Geyser Strokkur, Iceland's most famous geyser. © iStockphoto / Christoph Achenbach.

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Old Faithful Geyser - Yellowstone National Park
Old Faithful geyser of Yellowstone National Park blasts water about 150 feet into the air. © iStockphoto / Zuki.

El Tatio Geyser of Chile
Geysers of El Tatio, northern Chile.© iStockphoto / Rob Broek.

lady knox geyser new zealand
Eruption of Lady Knox Geyser, New Zealand. © iStockphoto / Halstenbach .

steamboat geyser
Steamboat Geyser of Yellowstone National Park. A rare eruption photo taken by E. Mackin, National Park Service in 1961.

old faithful geyser - yellowstone
The United States has two "Old Faithful" geysers, both of which produce predictable eruptions. This one is near Calistoga, California. © iStockphoto / Stephan Hoerold.

Great Fountain Geyser
Great Fountain Geyser at sunset, Yellowstone National Park. © iStockphoto / Geoff Kuchera.

strokkur geyser - Iceland
Strokkur Geyser is one of Iceland's most famous. It erupts to heights of seventy feet every ten to twenty minutes. © iStockphoto / Tetra2000.

geyser-like eruption on Jupiter's moon, Io
Eruption of Tvashtar, a "geyser" on Jupiter's moon, Io. NASA Image.

artists impression - enceladus geyser
Artist's impression of a cryovolcano on Enceladus.   NASA artwork by David Seals.

Enceladus remote sensing
Monochrome and Color-enhanced views of geyser activity on Enceladus. NASA Image.

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