The Mount Redoubt volcano across Cook Inlet continued to rumble Tuesday, with the alert code remaining yellow.

"It's pretty steady as she goes," said Tina Neal, a geologist with the U.S. Geological Survey. "We're still seeing small earthquakes every three or four minutes."

The volcano, which erupted last spring, grumbled back to life Sunday afternoon with a series of small quakes near the summit, prompting The Alaska Volcano Observatory to upgrade the volcano's alert status from green to yellow.

"In the past we've seen this kind of behavior, and it's ended in explosions or a collapse at some point," Neal said. "But we've also seen it quiet down to nothing. At this point it's hard to say which way she'll go. We're watching for some subtle changes in patterns."

Web cams on Tuesday showed no signs of steam. A pilot flying by also reported no steam. Scientists are planning to fly out to the volcano for a closer look on Thursday, Neal said.