The quakes are again picking up at Yellowstone and in western Montana, and the Steamboat Geyser is erupting again.
Geyser's activity puzzling
When the world's tallest geyser starts huffing, puffing and spewing, people pay attention.
So when Steamboat Geyser at Yellowstone National Park recently shot a plume of steam several hundred feet into the air, geyser watchers wondered whether it was erupting for the first time since May 2005.
There were other indications, too, including the draining of nearby Cistern Spring, often a telltale sign that Steamboat had ripped into one of its famous, and rare, eruptions.
But one thing was lacking: the thousands of gallons of water that flow out of Steamboat during those spectacular events.
One of the biggest questions now is whether the activity at the geyser, located at Norris Geyser Basin, is a sign that it's preparing for a major eruption.
The geyser fell quiet from 1991 to May 2000. Since then, seven major eruptions have been recorded, more than at any time since the early 1980s.
Park visitors and staff noticed some unusual activity at Steamboat on Feb. 11 and again 10 days later.
"Steamboat Geyser appears to be ready to erupt," said an e-mail from an observer on Feb. 22.
The biggest spikes in activity came around 2:40 a.m. on Feb. 11 and 2 a.m. Feb. 21.
Heasler and others checked on Feb. 23. Despite clear signs of activity, including the steam phase, snow around Steamboat didn't appear melted and there wasn't the scattered rock and other debris that tends to be stirred up in a major eruption, Heasler said. It was odd, too, to see that Cistern had drained but that nearby gauges showed no big discharge of water typical of a Steamboat eruption.
Fortunately, Norris Geyser Basin was recently wired with a network of gauges and monitors to track temperature, water flow, seismic movements and other activity. Heasler and others hope to review the records to see if there was anything unusual that might illuminate what happened in Steamboat's agitated state.