Volcano Monitoring

Due to the eruptions of 1980-86 and 2004-2008, Mount St. Helens has had the best seismic monitoring network of all volcanoes in the Cascade Range. It is also the most seismically active volcanoes in the Washington and Oregon Cascades.

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

Multiple types of camera images are used to monitor volcanic activity at Mount St. Helens including ground-based digital photographs, aerial photographs, and webcam images.

Gas released from a volcano relates directly to the type, amount, and depth of magma beneath the surface. Scientists measure the types and amounts of different volcanic gases to better understand a volcano's behavior. An increase in gas output or a change in the chemical make up of the gases can be some of the first above-ground signs of an increase in volcanic activity.

By analyzing thermal features of an erupting volcano scientists can better understand active volcanic processes.

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.

The chemical and physical characteristics of volcanic rocks can be studied during times of continuous eruption to help scientists better understand changes occurring within the volcano. This is called petrologic monitoring and is best used when combined with real-time and near-real-time data (such as seismic, deformation, and gas).

Monitoring sediment erosion, transport, and deposition.

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

When a volcano erupts explosively, an ash cloud will be produced. Its size and travel-distance are determined by the amount of material erupted, the height of the cloud, plus the wind directions and speeds. Knowing where the ash cloud might travel is critical for managing air space and warning downwind communities to be ready for possible ash fall.