Old Faithful Geyser, in Yellowstone National Park’s Upper Geyser Basin, is a prominent natural wonder. This iconic feature draws millions annually, captivated by its eruptions of hot water and steam. Known for its predictability, Old Faithful symbolizes the park’s dynamic geothermal landscape.
The Average Eruption Interval
Old Faithful typically erupts around 20 times daily. Intervals average 90 to 92 minutes, varying from 60 to over 110 minutes. Each eruption lasts 1.5 to 5 minutes, expelling thousands of gallons of boiling water.
Eruption heights range from 100 to 180 feet, averaging 130 to 140 feet. While consistent, the geyser operates within a predictable range, not on a precise clock. This variability means visitors should anticipate a waiting period to witness its display.
Factors Influencing Eruption Frequency
The primary factor determining Old Faithful’s next eruption interval is the duration of its previous eruption. Longer eruptions expel more water, requiring more time for the reservoir to refill and reheat. For instance, an eruption over 3.5 minutes results in a longer subsequent interval. This relationship helps park rangers and scientists forecast eruptions.
Old Faithful’s relative isolation from other thermal features in the Upper Geyser Basin contributes to its predictability. Its independent underground plumbing system, a network of cracks and fissures, allows water to seep in, superheat by magma, and build pressure until it flashes into steam, forcing an eruption. Seismic activity, like earthquakes, can also influence intervals by altering subterranean water levels or internal channels, leading to longer periods between eruptions.
How Predictions Are Made and Accessed
Park rangers and naturalists track Old Faithful’s eruptions to provide predicted times. They observe each eruption’s duration and height, key indicators for forecasting. This data is used to calculate upcoming eruption times with high accuracy, generally within a plus or minus 10-minute window.
Visitors can find these prediction times at various locations around the Old Faithful area. Information is posted at the Old Faithful Visitor Education Center, ranger stations, and other nearby buildings. The National Park Service also provides predictions through official Yellowstone apps and its webcam webpage, making it convenient for visitors to plan their viewing.
Reliability and Its Name
Old Faithful earned its name from the 1870 Washburn Expedition, who noted its consistent eruptions. While not precise, its “faithfulness” lies in its dependable, variable schedule. This reliability distinguishes it from many other erratic or dormant geysers.
Despite interval changes over decades, influenced by natural events like earthquakes, Old Faithful remains one of the most studied and predictable geysers globally. Its consistent performance provides insights into the complex geothermal processes beneath Yellowstone National Park.