Volcanic Hazards

Abstract

The damage and loss of life caused by volcanic eruptions are small compared with those caused by automobile accidents, wars, earthquakes and storms. However, volcanoes constitute a major threat to the ever-increasing number of people living on or near them. While most eruptions are small and their effects confined to the near vicinity of the crater, some volcanoes have the potential to unleash forces far beyond man's comprehension. Most to be feared is a major ignimbrite eruption, more than 100 times bigger and destructive than the 1980 eruption of Mount St Helens. It might place more than a million people at risk. Ignimbrite eruptions are rare events, but there seems to be a 1 in 5 probability that one will happen somewhere before the close of this century. Here the nature of volcanic hazards is reviewed and steps discussed that can be taken to recognize and quantify them for any specific volcano. Broad measures are considered which may be taken to minimize the risks from abortive eruptions, extinct volcanoes that come to life, and the large low-frequency events which present the greatest danger to man.