MOUNT ST. HELENS, Wash. -- The U.S. Geological Survey says an earthquake at Mount Saint Helens Monday sent a plume of ash and smoke nearly 20,000 feet into the air.

The earthquake had a magnitude of 3.1. Scientists also reported a large rockfall from the growing lava dome, which sent a flow of rock and dust from the new dome.

Seismic activity at the volcano is an every-day occurrence, but most of the recent quakes have stayed below two on the Richter scale.