Pressure continues to build inside Mount St Helens, one of the US's deadliest volcanoes, but fears of an imminent eruption are receding.
Geologists detected tremors in the crater and higher levels of gases in the air at the weekend and issued a level three alert.
They have since discussed lowering the state of alert.
Steam which rose from St Helens on Friday stirred fears of an eruption like that of 1980 which killed 57.
The most recent eruption came in 1986.
On Sunday, a tremor began which lasted about 25 minutes but it was gentler than a shuddering recorded on Saturday, which continued for nearly an hour.
"Right now, we're thinking it's about a 70% chance that it will erupt and a 30% chance that it just might go back to sleep," US Geological Survey geologist Tom Pierson told NBC's Today show on Monday.
'Weeks, not days'
Geologists have predicted that if an explosion does occur it will be on a far smaller scale than 1980.
Mr Pierson said that pressure was still mounting within the volcano.
Geological Survey crews observed a shift in the crater floor and on part of the 1,000-foot (300-meter) lava dome, which keeps down magma.
"Cracks are opening up so we know something is pushing up close to the surface right now," said Mr Pierson.
Experts discussed lowering the alert on Sunday.
Peter Frenzen of the US Forest Service, which looks after the immediate area, remarked that the volcano "reserved the right to change its mind".
Bill Steele at the University of Washington's seismology lab in Seattle warned that the activity in St Helens could go on for weeks.
"No one is predicting it as a sure thing," he said.
Evacuation
The volcano's level of seismic activity has prompted officials to evacuate hundreds of visitors from the nearest visitor centre - the Johnston Ridge Observatory, five miles (8km) away.
On Sunday, crowds gathered along a park road about 8.5 miles (14 km) from the mountain to wait and watch.
People lit barbecues and entrepreneurs sold hot dogs and coffee.
One viewer this weekend described the power exercised by the phenomenon.
"I just stare at it and stare at it - it's too awesome to leave," said Barbara Jardin, 53, of Camas.
On Friday, the volcano spewed a plume of steam and ash several thousands of feet into the sky.
When Mount St Helens erupted on 18 May 1980, the upper third of the mountain was blown off.
Gray ash buried towns and cities across the Pacific North-west, and forests and meadows were devastated.
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