Introduction

Reference: http://www.redcross.org/disaster/safety/guide/volcano.html

The United States is third in the world, after Japan and Indonesia, for the number of active volcanoes. Since 1980, as many as five volcanoes have erupted each year in the United States. Eruptions are most likely to occur in Hawaii and Alaska. For the Cascade Range in Washington, Oregon, and California, volcanoes erupt on the average of one to two each century. Volcanoes produce a wide variety of hazards that can kill people and destroy property. Large explosive eruptions can endanger people and property hundreds of miles away and even affect global climate.

Types and Effects of Volcano Hazards

Reference: http://volcanoes.usgs.gov/Hazards/What/hazards.html

Many kinds of volcanic activity can endanger the lives of people and property both close to and far away from a volcano. Most of the activity involves the explosive ejection or flowage of rock fragments and molten rock in various combinations of hot or cold, wet or dry, and fast or slow. Some hazards are more severe than others depending on the size and extent of the event taking place and whether people or property are in the way. And although most volcano hazards are triggered directly by an eruption, some occur when a volcano is quiet.

Volcanic eruptions are one of Earth's most dramatic and violent agents of change. Not only can powerful explosive eruptions drastically alter land and water for tens of kilometers around a volcano, but tiny liquid droplets of sulfuric acid erupted into the stratosphere can change our planet's climate temporarily. Eruptions often force people living near volcanoes to abandon their land and homes, sometimes forever. Those living farther away are likely to avoid complete destruction, but their cities and towns, crops, industrial plants, transportation systems, and electrical grids can still be damaged by tephra, lahars, and flooding.

Volcanic activity since 1700 A.D. has killed more than 260,000 people, destroyed entire cities and forests, and severely disrupted local economies for months to years. Even with our improved ability to identify hazardous areas and warn of impending eruptions, increasing numbers of people face certain danger. Scientists have estimated that by the year 2000, the population at risk from volcanoes is likely to increase to at least 500 million, which is comparable to the entire world's population at the beginning of the seventeenth century! Clearly, scientists face a formidable challenge in providing reliable and timely warnings of eruptions to so many people at risk.

Notable Volcanic Disasters

Reference: http://volcanoes.usgs.gov/Hazards/Effects/Fatalities.html

Since the year A.D. 1500, more than 300,000 people have died from volcanic activity. Most people were killed by only a few eruptions. For example, the huge explosive eruption of Tambora volcano in 1815 killed more than 90,000 people, primarily by starvation because the eruption destroyed crops and farmland. In the 20th century, eruptions at Mont Pelée and Nevado del Ruiz volcanoes killed more than 50,000 people. These examples demonstrate the importance of knowing the type and location of hazards associated with currently active and potentially active volcanoes. Planning for these hazards ahead of time can prevent future volcanic activity from becoming a disaster.

How to Protect Yourself During Ashfall

Reference: http://www.redcross.org/disaster/safety/guide/volcano.html

Volcanic ash is actually fine, glassy fragments and particles that can cause severe injury to breathing passages, eyes, and open wounds, and irritation to skin. Wear long-sleeved shirts and long pants. Use goggles to protect your eyes. Wear eyeglasses instead of contact lenses. Use a dust mask or hold a damp cloth over your face to help breathing. Keep car or truck engines off.

Hazards Prevention

Reference to Colleen M. Riley's web page: http://www.geo.mtu.edu/volcanoes/hazards/primer/

In recent years, with the eruptions of Mount St. Helens and Mount Pinatubo many advances have been made in the study of volcanoes particularly in eruption prediction. The problem with volcanoes is that, though there may be similarities between volcanoes, every volcano behaves differently and has its own set of hazards. That is why it's important for scientists to study and monitor volcanoes. Many active volcanoes near populated areas have not been sufficiently studied to assess risk.

When scientists study volcanoes, they map past volcanic deposits and use satellites to look at volcanic features, ash clouds, and gas emissions. They also monitor seismic activity, ground deformation, and geomagnetic, gravimetric, and geoelectrical and thermal changes at a volcano. They study and monitor volcanic gases and monitor the temperature, flow rate, sediment transport, and water level of streams and lakes near the volcano.

By studying volcanic deposits, scientists can produce hazard maps. These maps indicate the types of hazards that can be expected in a given area the next time a volcano erupts. Dating of these volcanic deposits helps determine how often an eruption may occur and the probability of an eruption each year. Monitoring of a volcano over long periods of time will indicate changes in the volcano before it erupts. These changes can help in predicting when an eruption may occur.

http://www.geo.mtu.edu/volcanoes/vc_web/Overview/o_health.html -- Revised: 26 DECEMBER 2002
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