SEATTLE, Washington, Oct 1 (AFP) - A plume of steam and ash erupted Friday from Mount St. Helens, the volcano that devastated swathes of the US northwest when it erupted 24 years ago, witnesses and geologists said.
"The mountain began erupting some steam (around 12:15 pm (1915 GMT))," said Mount St. Helens park ranger Greg Pohl after a colleague first spotted the plume.
"At the moment it looks like a very small event and there is an ash pall that appears to be very small that seems to be heading in a westerly direction."
Following the initial eruption, the volcano appeared to die down and the ash and steam clouded drifted off.
The steam cloud poured from the southern edge of a 300-meter tall (1,000-foot-tall) lava dome in the volcano`s crater that has risen in recent days, scientists said.
"This is exactly the kind of event we`ve been predicting," US Geological Survey scientist Cynthia Gardner told KOMO Radio news.
Officials notified aviation authorities to warn aircraft in the area of the steam and ash cloud, but said they did not believe there was any real danger to people who live in the region.
Seismologists at the US Geological Survey have been warning of a possible imminent eruption following more than a week of growing earthquake activity in the area.
A swarm of quakes began around the active volcano on September 24 and rose in magnitude through the week until they measured between 3.0 and 3.2 and were taking place four times a minute by Thursday.
But, the scientists stressed, any explosion of the peak would not be as serious as the deadly 1980 explosion that killed 57 people and covered much of the northwestern US region in a thick blanket of ash.