Passage IX
In 1789, Mt. Mantu erupted off the coast of Brunei releasing a cloud of ash that lowered global temperatures for 15 years. When a
volcano erupts, it releases a cloud of ash, dust, and debris into the atmosphere thousands of times the volume of the volcano. In addition, at the
time of the eruption, the volcano produces a mud and ash flow along the sides of the volcano. The ash flow around Mt. Mantu covered an area
30 times larger than the original size of the volcano. Figure 1 shows the volume of the ash clouds released by volcanoes of differing diameters
during the last 200 million years.
Figure 2 shows the average amount of time elapsed between consecutive major eruptions of various volcanoes of similar sizes, for a
range of volcano sizes. Figure 3 represents the percentage of land area covered by volcanic ash flows in three different mountain ranges—the
Cascades, the Appalachians, and the Himalayas—for various volcanic ash flow diameters.
Figure 1