Is Old Faithful Still Faithful?


Sitting on the benches surrounding Old Faithful, we joined the crowd in anticipation of the eruption.  However, the projected time came and went and we began to wonder if this would be the time Old Faithful breaks the cycle.

It wasn’t until about 10 minutes past the projected time that Old Faithful delivered once again to the awe and cheers of park visitors from all over the world, but we all wondered, is Old Faithful as faithful as it used to be?

Old Faithful predictably erupts 20 times per day in 90 minute intervals give or take 10 minutes with 90% accuracy even though the length of time between eruptions has gradually increased from 66.5 minutes between eruptions since 1938.

Has Old Faithful always been faithful? 

Although wood specimens from the geyser mound indicate during parts of the 13th and 14th centuries Old Faithful did not erupt at all, it has remained true to its name since its discovery in 1870 by the Washburn Expedition, with only slight changes in duration and intervals.  

In 1938 eruption intervals averaged 66.5 minutes. Since that time, intervals have slowly increased to an average of 90 minutes apart. 

Changes may be the result of earthquakes including the 1959 Hebgen Lake Earthquake and the Borah Peak Earthquake in 1983.  Prior to the 1983 earthquake, Old Faithful erupted 21 times per day. The current average is 20 times per day. 

Another change involves Old Faithful’s eruption modes.  Prior to a local earthquake in 1998, Old Faithful exhibited two eruptive modes: short duration eruptions followed by a short interval, and a long duration eruption followed by a long interval. Since that time, the eruptions are more often the long duration, long interval type. The length of eruption and interval factors into predicting the next eruption. 

What causes geysers to change their behavior?

Change is constant. Geysers have been described as fickle because predicting eruptions of most geysers has eluded scientists due to constantly changing environments.  Landslides and earthquakes affecting subterranean water levels can affect geyser behavior. Surrounding hydrothermal features can also affect neighboring geyser activity. Even rain and wind can have an effect. 

Steamboat Geyser, the largest geyser in the world, was unpredictable and dormant for years and then became quite active in 2018 and 2019.  It erupted 31 times in 2018 and then 8 more times by March 5, 2019. Eruption intervals ranged from four to 35 days.

In the fall of 2018 the Geyser Hill area experienced increased activity, including new vents which splashed water on the boardwalks.

A rare eruption of Ear Spring Geyser occurred on September 15, 2018 spewing a variety of foreign objects including coins and trash dating back to the 1930s.

Why is Old Faithful predictable when other geysers aren’t?

It is believed the regularity of Old Faithful Geyser is in part due to no connection with other hydrothermal features in the Upper Geyser Basin area. Predictable geysers are generally separate from other features or only connected to a feature whose activity is very steady.

Cross section showing the massive reservoir of water below Old Faithful (University of Utah)

Is Old Faithful the only predictable geyser?

There is another “faithful” geyser located in Calistoga, California.  It is called Old Faithful Geyser of California. It erupts every 15 to 45 minutes, and sprays water up to 60 feet high. The duration is generally about five minutes. This geyser has also been known to be a good predictor of earthquakes. When the geyser’s regular eruptions are delayed, an earthquake is likely within the next couple of weeks within a 500 mile area around the geyser. 

Several of Yellowstone’s geysers are somewhat predictable.  Daisy Geyser is one of the most predictable geysers in the park.  It is also in the Upper Geyser Basin of Yellowstone.  It erupts every 110 to 240 minutes for 3 to 5 minutes.  Its eruptions can be altered by nearby Splendid Geyser, Brilliant Pool or Comet Geyser activity. Its eruption interval decreased temporarily following the 2002 Denali earthquake but returned to previous intervals within a few weeks.

Rangers at the visitor centers can provide predicted eruption times for other geysers so you can plan to be near one of them around an eruption.  

Some of the more remote geysers have record logs located on site so visitors can log in the time and duration of eruptions.  Lone Star Geyser is one of these.  It erupts about every three hours and lasts for 30 minutes.

Eruption predictions for the following geysers are generally available at the Old Faithful Visitor Center.


Geyser

Location

Interval

Duration

Height

Old Faithful

Upper Geyser Basin

94 OR 68 min.

1.5 to 5 min

106-184


Castle


Upper Geyser Basin
13 hours 30 min.2nd major after a minor15-20frequent minor eruptions

75 ft.

Grand

Upper Geyser Basin
6 hours 30 min.8-12 min
160+ ft.


Daisy


Upper Geyser Basin
2 hours 45 min.+/- 30 minutes if windy

3.5 min.


75 ft.

Riverside
Upper Geyser Basin near Firehole River6 hours 30 min.
20 min.

75 ft.

Great Fountain
Lake Firehole Drive in the Lower Geyser Basin11 hours 30 min.
20 min.

75 ft.
Predictable geysers in Yellowstone National Park

How can I find geyser time predictions? 

Old Faithful eruptions are predicted with a 90% accuracy rate plus or minus about 10 minutes.  Predicted times of eruptions are calculated based on observation, timing with a stopwatch, and entering information into a log book. 

Prediction times are posted in most buildings in the Old Faithful area and on the webcam webpage. You can watch live streaming there, or download the official NPS app as well.

How to predict Old Faithful’s next eruption 

While watching, record the following:

  • Start Time (when water begins splashing continuously out of the cone)  _______
  • End Time (when only steam is coming out) _____
  • Length of Eruption (to nearest ½ minute) _____

Prediction is based on start time plus 68 minutes (if eruption was less than 3 minutes) 

OR

Start time plus 94 minutes (if eruption was more than 3 minutes)

Check the website for the next predicted eruption to see how close your prediction matched the rangers’.

What is underneath Old Faithful?

From the National Park Service Yellowstone webpage:

In the 1990s, researchers lowered a video camera into Old Faithful’s vent. Here’s what they found!

  • At 22 feet (6 m) underground, Old Faithful’s plumbing system shrinks to a few inches wide.
  • At 24 feet (7 m), a small waterfall of relatively cool groundwater flows into the conduit.
  • At 35–45 feet (10–13 m), a large cavern—about the size of a small car—lies inside Old Faithful.
  • A “liquid tornado” of wildly boiling, churning water at the lower end of the cavern stopped the camera from seeing any further.

Old Faithful Facts & Stats

Old Faithful Geyser is located in the Upper Geyser Basin near Old Faithful Lodge.
It was discovered in 1870 by the Washburn Expedition.
It was the first geyser in the park to be named.
Old Faithful Geyser erupts more frequently than any of the big geysers in the park.
More than 1,000,000 eruptions have been recorded since Yellowstone became a national park in 1872.
It is believed the regularity of Old Faithful Geyser is in part due to no connection with other hydrothermal features in the Upper Geyser Basin area.
Current number of eruptions per day: 20
Average interval between eruptions: 90 minutes
Length of eruption: 1.5 – 5 minutes
Amount of water expelled: 37,000- 8,400 gallons
Average height of water expelled from the geyser: 130 feet
Average temperature of water: 169°
Average temperature of steam: 350°
Old Faithful Facts and Stats

Conclusion

Many years ago a couple of young men pulled a prank at the Old Faithful site in Yellowstone.  They found a spot in the vicinity of the geyser but not obviously visible to spectators.  They proceeded to put a pipe into the ground with a wheel on the top. As Old Faithful began to erupt, the boys began turning the wheel, as if they were turning the geyser on.  They portrayed extreme exertion as they turned the wheel, as if they were unleashing the powerful stream of water into their air.  They made just enough of a commotion to attract the attention of some of the visitors, while pretending they thought they were out of sight. As the geyser receded, they again acted like they were “turning it off.”   They played the scene so well, people wondered if Old Faithful was a miracle of nature or a man-made attraction.

Old Faithful Geyser is a wonder to behold in the diverse landscape of Yellowstone. The forces of nature continually influence the landscape and hydrothermal activity of the region.  Man cannot turn it on or off.  In the constantly changing environment, will Old Faithful be able to continue it’s ever-dependable activity?  It depends on what nature has in store into the future. And we will keep going back again and again to test its faithfulness.

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