The world's tallest active geyser erupted in Yellowstone National Park on Thursday evening, according to a news release from the park.

 

Park employees reported seeing an eruption of Steamboat Geyser. Those reports, coupled with remote U.S. Geological Survey thermal sensors, have park geologists mostly convinced that the activity could be a series of minor eruptions.
USGS sensors were offline Friday. Staff will be troubleshooting equipment and may deploy new ones.
Steamboat is in the Norris Geyser Basin and is the tallest active geyser in the world.

Unlike Old Faithful, Steamboat's eruptions are unpredictable. Its last major eruption was on September 3, 2014.