Mt. Fitzherbert

MOUNT ST. HELENS NATIONAL MONUMENT, Wash. (AP) — A large part of the growing lava dome on Mount St. Helens fell Saturday, sending an ash plume above the crater rim, the U.S. Geological Survey reported. A rock fall had caused what scientists called a “substantial seismic signal” and knocked the chunk off the lava dome. The volcano was relatively quiet for the rest of the day.

The U.S. Geological Survey and the University of Washington have monitored the volcano closely since it rumbled back to life Sept. 23 with shuddering seismic activity that peaked above magnitude 3 as hot magma broke through rocks in its path.