ABSTRACT
There are two types of predictions with regard to volcanic and seismic hazards: (1) general prediction (long-term forecasting), is based on past behaviour to determine frequency. It uses historic catalogues and scientific records to produce probabilistic statements of future behaviour and is often used in conjunction with Geographic Information Systems to generate hazard maps; (2) specific prediction (short-term forecasting), which employs surveillance and monitoring to forecast the time, place and nature of events. Based on historic earthquakes (1522–2012), scientists have produced a Maximum Observed Intensity map for the Azores and detailed studies have been undertaken for São Miguel and also for the Central Islands. Following the damaging 1998 earthquake on Faial, a Vulnerability Index has been developed to assess current building stock. Specific prediction of earthquakes is still very much in its infancy, but monitoring is being progressively implemented across the Azores. General prediction (long-term forecasting) of volcanic eruptions dates from the 1980s when hazard maps of tephra dispersal from the central volcanoes of São Miguel were produced. In the following decades, more detailed hazard assessments were undertaken for Furnas and Fogo central volcanoes of São Miguel, which included a statistical forecast of the probability of future eruptions from Furnas volcano. In recent years, computer models have simulated the advance of lava and assessed the varying spatial susceptibility to inundation by flows. Other hazards, such as tsunamis, floods, landslides and degassing, are considered. Specific prediction (short-term forecasting) of volcanoes involves geophysical and geochemical techniques.
