“Old Faithful” – an American Wonder
Old Faithful is a cone geyser located in Yellowstone National Park,
Wyoming, United States. Old Faithful was named in 1870 during the
Washburn-Langford-Doane Expedition and was the first geyser in the park
to receive a name.
An eruption can shoot 3,700–8,400 gallons (14,000–32,000 l) of boiling
water to a height of 106–184 feet (30–55 m) lasting from 1.5–5 minutes.
The average height of an eruption is 145 feet (44 m).
The intervals range from 65–92 minutes with 91 minutes being the
More than 137,000 eruptions have been recorded. Harry M. Woodward first
described a mathematical relationship between the duration and intervals
of the eruptions (1938). Old Faithful is not the
tallest or largest geyser in the park. That title belongs to the less
predictable Steamboat Geyser.
Over the years, the length of the interval has increased, which may be
the result of earthquakes affecting subterranean water levels. These
disruptions have made the earlier mathematical relationship inaccurate,
but have in fact made Old Faithful more predictable. With an error of 10
minutes, Old Faithful will erupt 65 minutes after an eruption lasting
less than 2.5 minutes or 92 minutes after an eruption lasting more than
2.5 minutes. The reliability of Old Faithful can be attributed to the
fact that it is not connected to any other thermal features of the Upper
Between 1983 and 1994, four probes containing temperature and pressure
measurement devices and video equipment were lowered into Old Faithful.
The probes were lowered as deep as 72 feet (22 m). Temperature
measurements of the water at this depth was 244°F (118°C), the same as
was measured in 1942. The video probes were lowered to a maximum depth
of 42 feet (13 m) to observe the conduit formation and the processes
that took place in the conduit. Some of the processes observed include
fog formation from the interaction of cool air from above mixing with
heated air from below, the recharge processes of water entering into the
conduit and expanding from below, and entry of superheated steam
measuring as high as 265°F (129°C) into the conduit.
Old Faithful Geyser, short period eruption
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Old Faithful Geyser
Old Faithful Geyser during an eruption