After reviewing seismic and temperature data from sensors in the Norris Geyser Basin, scientists believe Steamboat Geyser, the largest in Yellowstone National Park, erupted at 5:30 a.m. (MDT) on Thursday March 15.

With most park roads closed for spring plowing, no one witnessed the eruption. Park employees reported seeing a significant steam plume late on the 15th, and park geologists shot this video on Friday, March 16.

Comparing first-hand reports with remote USGS thermal sensors, park geologists believe the activity could be a series of minor eruptions.

Like most of the park's geysers, eruptions of Steamboat cannot be predicted. In fact, Steamboat eruptions can be days or decades apart. When it does erupt, Steamboat reaches heights up to 380 feet. That makes it more than three times the size of Old Faithful and higher than any other active geyser in the world, an event that few people have witnessed.

According to the Yellowstone National Park website, the last time Steamboat Geyser erupted was September 4, 2014. To see current geyser activity in Yellowstone National Park, click here.