The Cascades Volcano Observatory (CVO) was established after the 1980 eruption to monitor any future activity in the area. Mount St Helens is just one of five active volcanoes in Washington and the information that the CVO gathers helps to provide an early warning system.

Earthquakes offer the earliest warning that a volcano may be active. They tend to come in 'swarms' just before most eruptions. The Cascades Range is monitored by seismograph stations which look out for signs of earthquakes. The size of the dome is monitored to examine if lava is escaping and geochemical studies of gases and temperature measurements are taken from fumaroles (small openings) on the mountain.

The CVO also has a real-time seismic-amplitude alarm system (RSAM) which is triggered by small volcanic events. This is particularly important for the Federal Aviation Authority (FAA) so that it can clear the airspace that may be affected by clouds of ash that are expelled during an eruption. Ash can wreak havoc with an aeroplane's engines, quickly clogging them up and trying to land on a slippery, ash-covered runway is extremely difficult and dangerous.

Other precautions include a dam built by the US Army corps of engineers, which should hopefully protect the immediate area and local inhabitants against possible landslides. The closest community is 30 miles away from Mount St Helens but in the event of an eruption there are plans in place for evacuation should this prove necessary.

The American Authorities have also published information on what the local population can do in the case of an ash fall. Residents should have face masks and eye protection, battery powered radios and torches and enough food and water for three days. When there are signs of volcanic activity, the area around Mount St Helens is closed to visitors and the roads through the National Park are shut to traffic.