Figure 1.12 General volcano structureCASE STUDIES
MOUNT SAINT HELENS: Located in Washington State, Mount Saint
Helens erupted in 1980. The earthquake removed trees, increased soil erosion,
destroyed wildlife, and polluted the air with gases and ash. Other effects
included mudflows, melting of glacial ice and snow, and clogged rivers that
caused flooding. Fifty-seven people were killed.
MOUNT PINATUBO: Mount Pinatubo is part of a chain of composite
volcanoes in the Philippines. In June 1991, Mount Pinatubo erupted for 9
hours, disgorged a cubic mile of volcanic debris, and vented 18 million metric
tons of sulfur dioxide into the atmosphere which encircled Earth in three
weeks after reaching the stratosphere. This was the largest sulfur dioxide
cloud ever detected. The sulfate aerosols formed in the stratosphere increased
the reflection of solar radiation and within 3 years caused over a 2°F (1°C)