Monitoring and predicting volcanic eruptions

Earthquake activity 

An increase in earthquake activity is an indication that magma is rising beneath a volcano causing, causing rocks to crack and fracture. Seisometerss are used to detect earthquakes. They pick up the vibrations in the earth's crust. An increase in vibrations may indicate a possible earthquake. 

Tiltmeters

Tiltmeters can be placed on the ground to measure slight changes in the tilt of the ground caused by rising magma. Global positioning systems (GPS) use satellite technology to measure very slight changes in distance of as little as 1mm. Laser beams can also be used to measure changes in distance between two fixed points on a volcano. If a volcano swells, the distance between two places will increase. 

Digital cameras

Digital cameras can be placed on the rim of craters to record small eruptions or landslides that may indicate rising magma. (e.g White island, New Zealand) Controlled from a distance, this is a safe way to monitor crater activity. Thermal imaging techniques and satellite cameras can be used to detect heat around a volcano. As activity increases, the temperature around the volcano increases. 

Gas Monitoring Stations

Gases emitted from a volcano, such as sulphur dioxide, can change in concentration prior to an eruption. Continuous gas monitoring stations are used by scientists to monitor activity at Kilauea volcano on Hawaii. The higher the sulphur content of the gases released, the closer the volcano is to erupting. A sudden increase in radon gas may suggest an earthquake. 

Historic information 

Historic information from previous eruptions can be used to construct hazard maps. This includes history of ash falls, lava flows and lahars. Hazard maps are used to identify zones at risk from particular hazards. They can be used to decide which areas are safe for developments such as housing and also in making plans for evacuations.