Uploaded February 2026 | Updated September 2026, 2 weeks ago
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Little Brother Geyser (13 August 2025)
Geysers are hot springs that episodically erupt columns of water. They occur in few places on Earth. The highest concentration of geysers anywhere is at the Yellowstone Hotspot Volcano in northwestern Wyoming, USA.
Little Brother Geyser is a moderately small, fountain-type geyser in the Myriad Group of Yellowstone's Upper Geyser Basin. It is often dormant, but is active during some seasons (e.g., 1983, 1999, 2009, 2011, 2013, 2016, and 2022 to 2025). The geyser is part of the Three Sisters Spring complex, which includes South Sister Spring, Middle Sister Spring, North Sister Spring (usually mis-referred to as an unnamed feature), Mugwump Geyser, Three Crater Geyser, an unnamed feature designated "UNNG-MYR-1", and Little Brother Geyser. Usually, the water level of the complex is high enough for all of those features to be submerged. Normally, Three Crater Geyser is the only regularly-active feature in the area. When active, Little Brother often has very frequent eruptions, with intervals as short as less than one minute. Many intervals are ~1 to 7 minutes, but they can be much longer and erratic. Eruptions are about 1 to 5 seconds in duration and involve one or more splashing spikes of water.
During ~3.5 hours of observation on 4 August 2025, Little Brother erupted 301 times. During most individual minutes, it would erupt once, twice, or three times. After the end of an eruption by nearby Three Crater Geyser, Little Brother would slow down for 8 or 9 minutes before resuming very frequent eruptions. After the end of a longer Three Crater Geyser eruption (= ~12 minutes in duration), Little Brother slowed down for about 12 minutes. In individual minutes during the slowdowns, Little Brother would have zero eruptions or one eruption only.
The same behavior was observed on other days in August 2025.
Little Brother Geyser videos:
youtube.com/playlist?list=PL8dL6UmmXTBUO5FahXtXpW0jUNo4U9Vpv
Filmed from the Three Sisters Spring pullout. Clips have been muted, due to annoying wind and vehicles.
All clips - Little Brother Geyser eruptions in the afternoon of 13 August 2025.
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Little Brother Geyser (13 August 2025)
Geysers are hot springs that episodically erupt columns of water. They occur in few places on Earth. The highest concentration of geysers anywhere is at the Yellowstone Hotspot Volcano in northwestern Wyoming, USA.
Little Brother Geyser is a moderately small, fountain-type geyser in the Myriad Group of Yellowstone's Upper Geyser Basin. It is often dormant, but is active during some seasons (e.g., 1983, 1999, 2009, 2011, 2013, 2016, and 2022 to 2025). The geyser is part of the Three Sisters Spring complex, which includes South Sister Spring, Middle Sister Spring, North Sister Spring (usually mis-referred to as an unnamed feature), Mugwump Geyser, Three Crater Geyser, an unnamed feature designated "UNNG-MYR-1", and Little Brother Geyser. Usually, the water level of the complex is high enough for all of those features to be submerged. Normally, Three Crater Geyser is the only regularly-active feature in the area. When active, Little Brother often has very frequent eruptions, with intervals as short as less than one minute. Many intervals are ~1 to 7 minutes, but they can be much longer and erratic. Eruptions are about 1 to 5 seconds in duration and involve one or more splashing spikes of water.
During ~3.5 hours of observation on 4 August 2025, Little Brother erupted 301 times. During most individual minutes, it would erupt once, twice, or three times. After the end of an eruption by nearby Three Crater Geyser, Little Brother would slow down for 8 or 9 minutes before resuming very frequent eruptions. After the end of a longer Three Crater Geyser eruption (= ~12 minutes in duration), Little Brother slowed down for about 12 minutes. In individual minutes during the slowdowns, Little Brother would have zero eruptions or one eruption only.
The same behavior was observed on other days in August 2025.
Little Brother Geyser videos:
youtube.com/playlist?list=PL8dL6UmmXTBUO5FahXtXpW0jUNo4U9Vpv
Filmed from the Three Sisters Spring pullout. Clips have been muted, due to annoying wind and vehicles.
All clips - Little Brother Geyser eruptions in the afternoon of 13 August 2025.
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