Cougar, Washington -- The eruption in the crater of Mount St. Helens is officially over, scientists said Thursday, leading the U.S. Geological Survey to lower the alert level for the volcano to "normal."

The eruption started in the fall of 2004 and pushed 125 million cubic yards of lava into the crater.

In the past 28 years, lava has replaced about 7 percent of the mountaintop that was removed in the 1980 blast.

Five months have passed with no earthquakes, gas emissions or ground deformation.

The Cascades Volcano Observatory in Vancouver said in Thursday's statement that the lava dome in the crater remains hot in places and is capable of minor explosions that could spread dust for tens of miles downwind. Small avalanches and mudflows also are possible.

"We know that Mount St. Helens will erupt again in the future in some mix of renewed dome building and more explosive behavior," said Cynthia Gardner, a scientist at the observatory. "However, at this point, we can't forecast when the next eruption will begin."