Prediction of volcanic activity

Prediction of volcanic activity, and volcanic eruption forecasting, is an interdisciplinary monitoring and research effort to predict the time and severity of a volcano's eruption. Of particular importance is the prediction of hazardous eruptions that could lead to catastrophic loss of life, property, and disruption of human activities.

Risk and uncertainty are central to forecasting and prediction, which are not necessarily the same thing in the context of volcanoes, where opinions have often played a role, and the prediction in time (forecasting) for an individual volcano is different from predicting eruption characteristics for apparently similar volcanoes. Both forecasting and prediction have processes based on past and present data.

Seismic waves (seismicity)

General principles of volcano seismology

Seismic activity (earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt and are a very important link to eruptions. Some volcanoes normally have continuing low-level seismic activity, but an increase may signal a greater likelihood of an eruption. The types of earthquakes that occur and where they start and end are also key signs. Volcanic seismicity has three major forms: short-period earthquake, long-period earthquake, and harmonic tremor.

Short-period earthquakes are like normal fault-generated earthquakes. They are caused by the fracturing of brittle rock as magma forces its way upward.