Old Faithful Geyser is located in Yellowstone National Park in Wyoming and is the most famous of all North American geysers. It spouts on an average of every 90 minutes. Ultimately, though, naturalists at Yellowstone have found that the geyser’s eruption can be predicted accurately only from one event to the next. Precisely when the next eruption will occur is determined by the duration of the preceding eruption: the longer an eruption, the longer the interval to the next eruption. The duration of Old Faithful’s eruptions ranges from 1.5 to 5.5 minutes. Billowing steam and 3,700 to 8,400 gallons of hot water are ejected at each eruption. The geyser’s fountainlike columns reach heights averaging about 130–140 feet, although eruption height can exceed 180 feet. During an eruption, the water temperature at the geyser’s opening is about 203–204 °F.
The Upper Geyser Basin has Yellowstone’s largest concentration of hydrothermal features and has long been the focal point for visitors to the park. The historic Old Faithful Inn (1903–04) is one of the country’s great national park lodges; Old Faithful Lodge (1918–28) and other vintage buildings are also in the vicinity. In 2010 Yellowstone park officials opened the Old Faithful Visitor Education Center. The facility provides park visitors with an opportunity to learn more about the geology, hydrothermal properties, and scientific study of Old Faithful and other hydrothermal features in the park.
If you would like to watch a video of Old Faithful, click on this link