Footage from an NPS webcam shows the geyser erupting as parkgoers look on.
According to the park service website, “infrequent but violent” eruptions characterize Giantess Geyser.
An eruption from the fountain-type geyser can cause the surrounding area to shake from underground steam explosions just before the initial eruptions.
Eruptions may occur twice hourly, and continue for four to 48 hours, according to the NPS.
When the geyser erupts, it typically shoots a stream that is 100-200 feet high.
The six-year gap between eruptions was the longest since at least the 1980s, but the geyser has had years-long dormant periods before, according to the agency.
“Why geysers turn off and on is something that is not well understood,” the USGS tweeted. “They are very fragile systems.”