Old Faithful is arguably the most famous geyser in the world. Its majestic eruptions have been captivating visitors to Yellowstone National Park for over a century. But beyond the iconic image, there’s a surprising amount you might not know about this geothermal wonder.
Not Exactly Faithful: Despite its nickname, Old Faithful’s eruptions aren’t precisely on the hour. While predictable, the interval between eruptions can vary from 44 minutes to 2 hours, with an average around 90 minutes. The good news is, scientists can still predict eruptions with impressive 90% accuracy within a 10-minute window [source: National Park Service].
Million Dollar Geyser: Since Yellowstone became a national park in 1872, Old Faithful is estimated to have erupted over 1 million times! That’s a staggering amount of water and steam expelled over the years, making this geyser a true natural marvel [source: Yellowstone Park Lodges].
Super Soaker Spectacular: Scientists estimate the amount of water expelled during an eruption ranges from 3,700 to 8,400 gallons (14,000 to 32,000 liters) That’s equivalent to 3 weeks of water usage for the average American household! [source: National Park Service]
Hot Enough to Make You Steam: The water temperature deep within Old Faithful can reach a scorching 400°F (204°C)! By the time it erupts, it cools slightly to around 204°F (95.6°C), which is still well above boiling at Yellowstone’s elevation. The steam, however, is even hotter, reaching a sizzling 350°F (177°C) – so be sure to keep a safe distance when enjoying an eruption [source: National Park Service ].
The Plumbing: Scientists don’t have a complete picture of what lies directly beneath Old Faithful, but thanks to research using seismic monitoring, they have a good idea of the geyser’s underground plumbing system:
- This superheated water doesn’t reach Old Faithful from directly beneath it. Instead, studies using seismic waves have revealed a large reservoir of hot water offset from the geyser by about 65 feet (20 meters).
- The hot water from the reservoir travels upwards through a network of cracks and fractures in the rock, not a single, straight pipe. As the water rises, it encounters a narrower section that acts like a “bubble trap.” Here, the water boils and creates steam bubbles, building pressure until the eruption occurs [source: U.S. Geological Survey].
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Sources:
https://www.nps.gov/yell/planyourvisit/geyser-activity.htm
https://www.yellowstonenationalparklodges.com/lodgings/hotel/old-faithful-inn/
https://www.usgs.gov/news/a-new-view-old-faithfuls-underground-plumbing-system)
