Early Warning Systems (EWSs)

Abstract

Prediction of natural and human-assisted or intensified hazards is the basis for EWSs. We will give a general assessment of EWSs here and discuss their status in some detail later in the text when treating specific hazards. At present, for natural hazards, there are EWSs that can be put in place for flood hazards that are accurate in terms of where and when they will occur, the level above stream/river banks flood waters will rise, how long before a location will be flooded and how long flood stage will last. EWSs for volcanoes that are coming into an eruption stage can be established that are generally accurate as to when there will be an eruption, whether a volcano will launch tephra or emit lava and where it will flow, but can not accurately predict the force of an eruption nor how long it will last. There are EWSs signs of landslides that are related to topography, observations of slow earth movement, and amount of rainfall an area has received but these are often missed.