8. Can volcanic eruptions be predicted?

Volcanic eruption prediction includes activities aimed at understanding the functioning mechanisms of the volcano evaluating the probability of an eruption in a given area, with a given intensity (magnitude) and for a given period.

Prediction activities are carried out by scientists and experts as the assessments needed are based on:

  • the study of the dynamic of the geological system and of the volcano;
  • study of the history of the volcano;
  • estimation of the probability of different eruption types;
  • identification of areas and sites at risk.

Though there may be similarities in the general functioning of volcanoes, every volcano behaves differently and presents a specific hazard; it is thus very important for scientists to study and monitor each single volcano separately.

Volcanoes monitoring is made through:

  • Physical parameters:┬ámostly used to detect the underground deformations induced by the displacement of the magma (seismic activity; ground deformation; geomagnetic, gravimetric and geo-electrical fields; water levels in sources and lakes, etc.);
  • Geochemical parameters:┬ámostly used to detect magma changes generating its displacements towards the surface (gas, water and lava are analyzed to assess their flow rate and quantity as well as their composition and temperature).
The USGS monitoring network of the Yellowstone National Park volcano. Source: United States Geological Survey
The seismic monitoring network on vesuvius. Source: Vesuvius Observatory
Geodetic (ground deformation) network on Vesuvius. Source: Vesuvius Observatory
Gravimetric (differences in density of underground bodies) network on Vesuvius. Source: Vesuvius Observatory

By studying volcanic deposits, scientists can produce maps indicating the types of hazard that can be expected in a given area if the volcano erupts (hazard maps). Dating of volcanic deposits helps to determine how often an eruption may occur and what is the probability of an eruption in a given period of time (25, 50, 100, 1000 years).

Only through the monitoring of a volcano over a long period of time it is possible to detect physical and geochemical changes in the volcano, possibly announcing an eruption.

Such a probabilistic assessment of the volcanic hazard allows scientists and land developers to assess the risk level(s) and the public authorities to plan measures to reduce the actual risk.