A GLOBAL PERSPECTIVE ON VOLCANOES AND ERUPTIONS

In the past 10,000 years, about 1500 volcanoes have probably been active, geologists say. The earth's active volcanoes include about 10 or 15 that are almost continuously erupting. During the 1990s, each year saw about 50 or 60 volcanoes erupting. Many of the 1500 volcanoes are on land or protrude above water. There are many more volcanoes deep beneath the sea that remain unwatched. Their eruptions do not generally break the surface. Volcanoes are often located in chains or linear belts. The volcanoes along the Pacific Rim are often explosive when they erupt. Many air routes from Asia pass over part of the Philippines, Japan, and Indonesia. These countries, together, are the home of more than one third of the world's active volcanoes. Many eruptions begin suddenly, however, they can also often be preceded by years of smaller discharges. Many of the volcanoes in the world are not equipped with dedicated monitoring instruments. About one half of the worlds 1500 active volcanoes are located in developing countries.