Deformation

Mount St. Helens' high frequency of eruptions during the recent geologic past and its two eruptive episodes of the past three decades indicate a high probability of renewed eruptive activity.

Studying the ground surface movement around a volcano (also called deformation) can give clues to what is happening beneath the surface.

Magma began intruding into the Mount St. Helens edifice in the late winter and early spring of 1980. By May 18, the cryptodome (bulge) on the north flank had likely reached the point of instability, and was creeping more rapidly toward failure.

New techniques for monitoring volcanoes and instruments that take advantage of new technologies are often employed by volcanologists when they are affordable and minimize exposure of personnel to hazards.

At Mount St. Helens, scientists use Digital Elevation Models (DEMs) to monitor changes to topography around the volcano. For instance, overlapping DEMs are used to calculate the volume of lava erupted and the rate of dome growth, volume and growth of Crater Glacier, measure debris flow thickness, study sediment transport in streams and rivers, and monitor changes to stream chan