Sprinkler Geyser eruption (2:28-2:48 PM, 10 August 2018)
Geysers are hot springs that episodically erupt columns of water. They occur in few places on Earth. The highest concentration of geysers anywhere is in Yellowstone’s Upper Geyser Basin (northwestern Wyoming, USA).
Sprinkler Geyser is in the Castle Group of Yellowstone's Upper Geyser Basin. It is located about 5.5 to 6 meters from the southern banks of the Firehole River, ~108 meters upstream from the Castle-Sawmill bridge. It has an irregularly-subcircular geyserite crater about 3 to 4 meters across. A smaller, rarely-seen geyser called "Sprinkler B Geyser" occurs just to the northeast of Sprinkler. Eruptions of Sprinkler Geyser are frequent. It is erupting more than 50% of any given time interval. Eruptive activity can be seen from the Castle-Sawmill bridge, from the boardwalk near Liberty Pool (= the best viewing spot), from the boardwalk in the western Geyser Hill Group, and via the Old Faithful web camera. Intervals (= eruption start to eruption start) are usually 20 to 30 minutes apart. Eruption durations vary and are difficult to quantify. Web camera and on-site observations indicate that eruptions gradually decrease in spouting height and splashing intensity. A complete eruption seen on 10 August 2018 was ~20 minutes long (if an eruption is defined as the first appearance of erupting water to the last appearance of water that was spit above the crater rim). The next eruption start after that was 7 minutes later.
Web camera and on-site observations have shown that Sprinkler Geyser sometimes does not cease eruptive activity 20 to 30 minutes after an eruption start. Instead, eruptive energy increases, but activity is a continuation of the "previous" eruption. These "double-length" eruptions are uncommon.