Mt. Saint Helens seismic events: Volcanic earthquakes or glacial noises?

Low frequency seismic events have been recorded on Mt. Saint Helens, an historically active stratovolcano in the Cascade Range of Washington State. While the character of the events is similar to volcanic seismic events recorded on active volcanoes in many parts of the world, the seismic evidence gathered during an experiment on Saint Helens indicates the glaciers on the mountain as the source of the low frequency activity. The experimental results illustrate the current problem of predicting volcanic behavior from seismic data in such geophysically complex areas as glacier‐clad volcanoes.