What Are Geysers?
The word "geyser" means "to gush," referring to the movement of the water when a geyser erupts. Geysers are underground springs of water that intermittently eject water and steam. Geysers are always located near areas of volcanic activity.
Inside a geyser, there is a reservoir that holds the water and "pipes" of rock - fractures, cavities, and porous areas. Why do geysers spew out hot water? Surface water from rain and rivers trickles down through the earth, reaching a depth of nearly 7,000 feet (2,000 meters). There, it comes into contact with rocks heated by molten magma deep below the earth's surface. The water boils, creating pressure. The water and steam are pushed to the surface and erupt from the surface vent. This is called a hydrothermal explosion (hydro means "water," and thermal means "heat").
Steam driven geysers can be divided into two types - fountain geysers and cone geysers. Fountain geysers erupt from beneath pools of water, usually in short bursts of a few seconds each. The vents of cone geysers, on the other hand, consist of mounds of minerals. Cone geysers may erupt continuously for several minutes - some even erupt for more than an hour at a time.
Geysers don't last forever. Earthquakes, human activity, the movement of tectonic plates, and other factors can cause a geyser to stop functioning. Even throwing garbage into a geyser may change its conditions enough to cause it to go dormant.
Cold Water Geysers
Another type of geyser is called a cold water geyser. Instead of heat driving the water from the ground, carbon dioxide (CO2) collects in underground lakes called aquifers. The weight of the water contains the carbon dioxide bubbles until the rock layer above weakens and forms a fissure, or crack, or when humans drill through the rock. Then, the bubbles expand and propel the water upwards with great force. Only a few of this type of geyser exist, located in the United States, Germany, Slovakia, and Brazil.
Geysers are not only found on Earth. Scientists have observed geysers of chemical vapors with low boiling points, ice, and dust, on other planets and their moons, such as Mars and the moons of Saturn and Neptune. They call these cryogeysers - cryo means "icy cold".
Over one thousand geysers are active around the world. Being a relatively rare phenomenon, tourists often visit geysers to see the water spray high into the air. The following are a few of the most well known geysers.
- Old Faithful. Perhaps the most famous geyser in the world, Old Faithful is a cone geyser located in Yellowstone National Park in the United States. This geyser is called old faithful because it is very predictable, with eruptions occurring every forty-four to one hundred and twenty-five minutes. Yellowstone National Park is home to more geysers than anywhere else in the world, with as many as five hundred active geysers observed each year.
- Steamboat Geyser. Located in Yellowstone National Park not far from Old Faithful, the Steamboat Geyser is the tallest currently active geyser in the world. The Steamboat Geyser regularly expels water more than three hundred feet (90 meters) in the air. This geyser is dormant at times, with the length of time between eruptions ranging from a few days to more than fifty years.
- The Great Geysir. Located in Iceland, this geyser was discovered during the 14th century. The word "geyser" is derived from its name. While this geyser is often dormant, it is induced to erupt on special occasions by the addition of certain chemicals.
- Strokkur Geyser. Also located in Iceland, the Strokkur Geyser is known for erupting every five to eight minutes.
- El Tatio. El Tatio is a field of eighty geysers located near active volcanoes of the Andes Mountains in Chile. El Tatio means "oven" in the local Quechua language, describing the geothermal heat. This area is known for its low geysers. Most of the geysers divulge water only to a height of thirty inches (750 millimeters), with the tallest reaching a height of twenty feet (6 meters).