The Workings of a Geyser
The Old Faithful Geyser of California is one of three geysers in the world with the designation "old faithful." These are the geysers that perform at regular intervals. A geyser exists only where conditions are right. These conditions include a natural deep subterranean supply of water, a source of heat and a series of fissures, fractures and cavities that provide a path to the surface of the earth. Surrounding rock formations must be strong enough to maintain continual onslaughts of the intense pressure of steam and water explosions.
Water for the Old Faithful Geyser of California comes from an underground river. When this water flows over the hot molten magma deep in the earth, it boils and expands and is collected in large cavities. Under tremendous pressure from the heat, and assisted by a constriction of the passage upward, the superheated water is forced through the fissures and fractures and erupts with an outpouring of steam followed by a fulmination of hot dancing water.
Visitors of Calistoga's Old Faithful Geyser are calling it "utterly amazing". The Geyser is one of only three Old Faithfuls in the world, designated as such because of its constant and predictable eruptions. This spectacle is a true rarity, and there's no better place to see it than here!

The Geyser is an all-natural phenomenon which tosses a scalding curtain of water anywhere from 20 to upwards of 75 feet into the air. Currently, Old Faithful is erupting approximately every 20-30 minutes.
Under normal conditions, the water, the heat and the underground structure all remain constant and for this reason Old Faithful erupts regularly. Conditions which cause deviations from the normal pattern seem to relate to earthquakes. The Old Faithful Geyser of California is proving itself a predictor of quakes.