MOUNT ST. HELENS, Wash. -- Scientists said the earthquakes and explosions at Mount St. Helens could lead to an eruption as powerful as the one in 1980, KIRO 7 Eyewitness News reported.

The volcano reportedly spewed more steam overnight, but earthquakes continued to be fairly light, striking about once a minute and registering about magnitude one.

Meanwhile, the speculation continued about what exactly is happening underneath the mountain.

Scientists said part of the lava dome in the volcano's crater has risen 50 to 100 feet since Tuesday, a sign -- along with mild earthquake activity -- that molten rock may be moving toward the surface without much resistance.

The south side of the dome has been rising for the past week -- about 250 feet so far.

Despite the swelling, scientists said there is no reason yet to raise the alert level around the volcano in southwest Washington.

Larry Mastin of the U.S. Geological Survey said there's an outside chance that an eruption could send a plume of ash 15 miles into the air or higher, but there is no indication that any eruption is imminent or that it would threaten lives or property.

There's also no way to tell when molten rock might reach the surface, although the volcano has been venting steam as water trickles down and hits hot rocks.