Geysers get their name from Geysir, in Iceland. Geysir used to be a great attraction, and more than one early travel writer marveled at its 80-meter-high boiling fountains. Alas, those same 18th- and 19th-century tourists threw so many rocks into Geysir's throat that for many years he stopped spouting.
This great erupting hot spring is an eponym—something or someone that gives its name to everything of its type. Geology has at least two other eponyms—for instance, every volcano on Earth is named for Vulcano, in the seas off Italy.
What a Geyser Is
A geyser is a hot spring—a very deep, very hot spring in which the bottom water is steadily heated, kept from boiling by the pressure of the water above it. When the heat overcomes the pressure, boiling begins. The more the steam from the boiling pushes up the water column, the more water flashes into steam, and the feedback cycle builds into an eruption. Once the hottest water is blown out, cooler water flows into the geyser's plumbing, and the cycle begins again.
Geysers interest geologists because they are blood samples from the underground. Deep hot water is part of the complex doings that form ore deposits, so geysers help shed light on a very basic scientific problem. Another aspect of geyser fields is that the extreme conditions harbor some strange organisms that are usually found deep underground. Some of these extremophile microbes give us clues about how life exists in the harshest places (such as in strong acids or seafloor black smokers), and how it might exist on other planets.
America's foremost geyser field, at Yellowstone National Park, is also the world's greatest. The young volcanic rocks there energize nine major geyser basins containing hundreds of features, ranging from humble mudpots to Old Faithful. There are lesser-known geysers elsewhere around the west. In California, the steam field called The Geysers is the world's largest geothermal energy plant. The geysers it once had are gone today. Not far away, though, in the Napa Valley is a humble spouter in Calistoga that is also called Old Faithful. WyoJones' Geysers Page says that this Old Faithful is actually a drilled hole that's been periodically reamed out since around 1870. So although the geysering action is authentic, the geyser is something of a Disney geyser.
But this little Old Faithful is of special interest to California geologists. Its position, in the middle of the wide fault zone that causes many earthquakes, seems to make it a sensitive gauge of underground stress in the whole region. Luckily, good records have been kept of its eruptions since 1973. A few years ago, when scientists first learned of this trove of data, they found that the geyser's activity changed in the weeks before three significant earthquakes. One was hundreds of kilometers away. However, they also found that its activity changes all the time anyway, so nothing was revealed.
The Yellowstone geysers, though, really do respond to distant earthquakes. The great Alaska earthquake of November 2003, more than 3000 kilometers away, caused the geysers to change their schedules or erupt erratically for some time. Clearly they are not stable, long-lived phenomena. Like rock formations in other energetic settings such as the seashore, geysers have short lives, geologically speaking.
Geysers—A Threatened Species
For the rest of us who aren't geologists, geysers are just really cool things. Their animation, their energy, their personalities make them natural magnets for visitors. You can visit them in Iceland, the Azores, Peru, Chile, New Zealand, and Costa Rica as well as at Yellowstone. The lesson of Geysir has been learned well, and the humans are fenced off from the performers. For the true primordial steam-in-the-face geyser experience, the place to go is in deepest Kamchatka in the Valley of the Geysers, two hours by copter from Russian civilization.
Though tourists are now a threat kept in check, the energy industry remains the world's worst killer of geysers. Geothermal power producers drill for steam and inevitably disturb the delicate chain of heat and chemistry that sustains geysers. Thus it was that, only a few years ago, power plants destroyed the large but little-known Beowawe geyser field and the Steamboat Springs field, both in Nevada. After reading about these and other vanished geysers on WyoJones' site, you may shed a tear for this endangered species.
PS: A third geologic eponym is the man whose name was given to the guyot ("ghee-oh"), a type of flat-topped mountain found by the thousands on the world's seafloor. There is no guyot named Guyot. Arnold Henri Guyot was a Swiss-American geologist who taught at Princeton for 30 years. There he's not just a landform, he's a building, too. And movie star Marilyn Monroe is a geologic eponym, having inspired the name "monroes" for small, highly rounded sediment mounds in certain tidal flats.