A reawakening volcano sparked a makeshift festival here Sunday, as thousands of people staged parties at every wide spot in the two-lane road to the mountain.

Geologic spectators set up lawn chairs in the beds of pickup trucks and fired up barbecues from the park entrance to the Coldwater Ridge Visitor Center at Milepost 43, where the road is closed 81/2 miles from the simmering volcano. Impromptu entrepreneurs hawked hot dogs and coffee.

At the futuristic visitor center, with a view straight into the crater, the wraparound veranda was jammed with people in lawn chairs -- most of them with cameras.

"It's beyond amazing," said Steven Uhl, 31, of Everett, who has tried to visit every year since 1982. "I've been a volcano nut since 1980. . . . Just to be here is almost a religious experience."

Thermal images of the volcano, along with the detection of potentially explosive gases and continued tremors early Sunday morning, indicated that new magma is still moving upward into the volcano, said scientists awaiting the next eruption.

U.S. Geological Survey scientists said they are seeing hot spots and emissions of hydrogen sulfide and carbon dioxide typically associated with a magma move in a volcano.

A harmonic tremor -- a sustained, deep movement of the earth within the volcano -- was detected about 6 a.m. Eastern time. Scientists said it is further evidence of how active the volcano might be.

Looking at the Volcanic Explosivity Index, which measures the power behind an eruption, scientists predicted a 50 percent chance of a new eruption reaching Level 2 on the scale from 1 to 10, and a 30 percent chance of a Level 3, according to a preliminary estimate from Thomas Pierson, a USGS hydrologist. By comparison, Friday's combined steam and ash cloud measured less than 1 on the index, while the 1980 eruption measured 5.

Spectators were prepared to capture the moment. Chris Sawyer, 40, of Dundee, Ore., had a large camera with a zoom lens set up on a tripod in what he hoped was a good spot.

"I hope to see something," he said. "It'd be neat if it spews something over and out."

Nearby, an artist known as "O" from Santa Monica, Calif., was working on a 4-by-5-foot painting of the mountain, using three dozen cans of bargain house paint in various tones, mostly grays, blues and olives.

Officials believed people were "out of harm's way" at Coldwater Ridge, said Peter Frenzen, monument scientist for the U.S. Forest Service, which oversees the mountain and surrounding Gifford Pinchot National Forest.