Mount St. Helens goes back to sleep

VANCOUVER, Wash., July 11 (UPI) -- U.S. scientists said Mount St. Helens appears to have returned to slumber after more than three years of activity.

The U.S. Geological Survey has lowered the volcano alert level from "advisory" to "normal" and the aviation color code from yellow to green, the agency said Friday.

"Five months have passed with no signs of renewed eruptive activity," said scientists at the USGS Cascades Volcano Observatory. "Earthquakes, volcanic gas emissions, and ground deformation are all at levels seen before the eruption began."

The volcano, which killed 57 people when it erupted violently in 1980, reawakened in October 2004 with blasts of steam and ash. Growth of a lava dome continued until January.