Volcano monitoring
Volcano monitoring is the systematic observation of volcanic activity and its surroundings to detect changes, assess hazards, and inform warnings.
Seismology: The study of earthquakes and seismic waves generated by sources within Earth. Earthquake patterns can reveal magma movement and changes in volcanic conduits.
Volcanic alert level: A public status category expressing a volcano's current activity or associated hazard. Agencies translate monitoring evidence into alert levels for authorities and communities.
Magma: Molten or partially molten rock beneath Earth's surface, containing dissolved gases and crystals. Magma movement and pressure changes generate many of the signals monitoring seeks.
Mount St. Helens: An active stratovolcano in Washington State that erupted catastrophically on May 18, 1980. Its 1980 eruption demonstrated both the value and limits of forecasts based on observed unrest.
Ground deformation: Changes in Earth's surface shape or position caused by geological processes. Inflation, subsidence, and shifting slopes can signal pressure changes beneath a volcano.
Volcanic early warning system: An arrangement for detecting volcanic threats and communicating warnings before impacts occur. Monitoring provides the observations that trigger and update volcanic warnings.
Volcanic eruption: The release of magma, gas, ash, or other material from a volcano. Monitoring distinguishes background activity from changes that may precede an eruption.
Pinatubo eruption: The 1991 eruption of Mount Pinatubo in the Philippines, which produced a major caldera-forming event. Monitoring helped forecast the eruption and support large-scale evacuations.
Volcanic gas: Gases emitted by volcanoes, including water vapor, carbon dioxide, and sulfur dioxide. Changes in gas composition or emission rates can indicate changes in magma supply.
Volcanic hazard map: A map showing areas exposed to volcanic hazards and their likely distribution. Monitoring can refine hazard assessments as activity and eruption scenarios change.