How Geysers Work

Rare and Beautiful Geological Formations

Old faithful geyser erupting with sunset in the background
View of the Old Faithful Geyser in Yellowstone National Park as it erupts against a dark sky, Wyoming, 1941. Getty Images

Right now, in a few rare places on Earth, people are enjoying the sight and sound of superheated water rushing from deep below ground and into the air. These unusual events, called geysers, exist on Earth and throughout the solar system. Some of the most famous geysers on Earth are Old Faithful in Wyoming in the United States and the Strokkur Geyser in Iceland.

Geyser eruptions happen in volcanically active areas where superheated magma sits fairly close to the surface. Water trickles (or rushes) down through cracks and fractures in the surface rocks. These fractures can reach a depth of more than 2,000 meters. Once the water s rocks heated by volcanic activity, it starts to boil and the pressure rises on the system. When the pressure gets too high, the water blows out as a geyser, sending a rush of hot water and steam into the air. These are also called "hydrothermal explosions." (The word "hydro" means "water" and "thermal" means "heat.") Some geysers shut down after mineral deposits clog up their pipes.

How Geysers Work

The mechanics of a geyser and how it works. Water seeps down through cracks and fissures, encounters heated rock, is heated to superboiling temperatures, and then erupts outward. USGS

Think of geysers as natural plumbing systems, dealing only with water heated deep within the planet. As Earth changes, the fields do, too. While active geysers can be easily studied today, there's also ample evidence around the planet of dead and dormant fields. Sometimes they die out due to clogging; other times they've been mined or used for hydrothermal heating, and eventually destroyed by human activity.

Geologists study the rocks and minerals in geyser fields to understand the underlying geology of the rocks below the surface. Biologists are interested in geysers because they support organisms that thrive in hot, mineral-rich water. These "extremophiles" (sometimes called "thermophiles" due to their love of heat) give clues to how life can exist in such hostile conditions. Planetary biologists study geysers to better understand the life that exists around them.

The Yellowstone Park Collection of Geysers

Old Faithful geyser at Yellowstone National Park. This one erupts about every 60 minutes and has been probed with space-age cameras and imaging systems. Wikimedia Commons

One of the most active geyser basins in the world is at Yellowstone Park, which sits atop the Yellowstone supervolcano caldera. There are around 460 geysers rumbling at any given time, and they come and go as earthquakes and other processes make changes in the region. Old Faithful is the most famous, attracting thousands of tourists throughout the year.

Geysers in Russia

Valley of the Geysers in Kamchatka, Russia. This picture was taken just prior to a mudflow that engulfed some of the geysers. This remains a very active region. Robert Nunn, CC-by-sa-2.0

Another geyser system exists in Russia, in a region called the Valley of the Geysers. It has the second-largest collection of vents on the planet and is in a valley about six kilometers long.

Iceland's Famous Geysers

Strokkuer Geysir erupting, November 2010. Copyrighted and used by permission of Carolyn Collins Petersen

The volcanically active island nation of Iceland is home to some of the most famous geysers in the world. They are associated with the mid-Atlantic Ridge. This is a place where two tectonic plates—the North American Plate and the Eurasian Plate—are slowly moving apart at a rate of about three millimeters a year. As they move away from each other, magma from below rises up as the crust thins. This superheats the snow, ice, and water that exist on the island during the year, and creates geysers.

Alien Geysers

geysers on Enceladus
Plumes of water ice crystals, possible cryogeysers, jet out from cracks in Enceladus's south polar region. NASA/JPL-Caltech/Space Science Institute

Earth isn't the only world with geyser systems. Anywhere that interior heat on a moon or a planet can warm up water or other ices, geysers can exist. On worlds such as Saturn's moon Enceladus, so-called "cryogeysers" spout, delivering water vapor, ice particles, and other frozen materials such as carbon dioxide, nitrogen, ammonia, and hydrocarbons. Decades of planetary exploration have revealed geysers and geyser-like processes on Jupiter's moon Europa, Neptune's moon Triton, and possibly even distant Pluto. Planetary scientists studying activity on Mars suspect that geysers can erupt at the south pole during spring heating.

How Geysers Where Named and Where they Exist

geyser locations on Earth
The location of geysers around the world. A careful examination shows them to be related to tectonic and volcanism in each spot. WorldTraveller, via Wikimedia Commons, Creative Commons Share-Alike 3.0.

The name for geysers comes from an old Icelandic term "geysir", a name shared with a huge erupting water field in a place called Haukadalur. There, tourists can watch the famous Strokkur Geysir erupt every five to ten minutes. It lies amid a field of hot springs and bubbling mud pots. 

Using Geysers and Geothermal Heat

gesyers and geothermal heat
The Hellesheidi Power station in Iceland, which uses boreholes to capture heat from underground geothermal deposits. It also provides hot water to nearby Reykjavik. Creative Commons Attribution 2.0

Geysers are extremely useful sources of heat and electricity generation. Their water power can be captured and used. Iceland, in particular, uses its geyser fields for hot water and heat. Depleted geyser fields are sources of minerals that can be used in various applications. Other regions around the world are starting to emulate Iceland's example of hydrothermal capture as a free and fairly unlimited source of power.