Updated

Government scientists said Wednesday that the danger of a strong Mount St. Helens (search) eruption at any moment has passed, but warned the mountain could continue venting steam and volcanic rock for several weeks.

"We no longer think that an eruption is imminent in the sense of minutes or hours," Willie Scott, a geologist with the U.S. Geological Survey (search), said after scientists reported a lower level of seismic activity at the mountain.

Volcano Cam

The changes prompted scientists to lower Mount St. Helens' alert level from three to two. Level three is the highest.

"There's not necessarily going to be a big one," said Jake Lowenstern, a USGS volcanologist. "People have to get that out of their minds."

Nevertheless, Scott cautioned that the mountain is far from turning dormant. "We have to warn people that the volcano is in a state now where we could go into accelerating unrest or eruption quite quickly," Scott said.

Since Sept. 23, thousands of tiny earthquakes have shaken the mountain and several steam eruptions have occurred in the last five days, the most seismic activity (search) at the peak since the months following its catastrophic 1980 eruption.

An hour-long blast Tuesday morning was the largest, sending a roiling, dark gray cloud thousands of feet over the 8,364-foot peak.

The spectacular cloud delighted visitors to the mountain but gave an unwanted dose of the gritty, abrasive dust to areas to the northeast, including the small town of Randle about 25 miles away. The town's two schools kept students with asthma inside, and postal workers were given face masks in case they encountered ash.