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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Volcanoes and the Environment
By
The environmental impact of volcanoes is far reaching
and while the destructive effects are the ones commonly
associated with volcanoes, the overall impact is certainly
beneficial. The destructive effects of volcanic eruptions, such
as lava flows, ash falls, hot avalanches, and mudflows are
briefly reviewed. The most dangerous and least predictable
are mudflows, such as the one that destroyed Herculaneum
in the 79 A.D. eruption of Vesuvius. Mt. Rainer and other
volcanoes of the Cascades are potential sites for destructive mudflows. The possible
intent of such flows, based on past
history, is considered.
The major environmental impact of volcanoes is in their
effect on climate and soils. The huge quantity of ash ejected
into the atmosphere in a major eruption results in a decrease
in the solar radiation and a lowering of the temperature. The
unusually cold weather throughout the world in 1816,
commonly known as the "year without a summer", coincided
with the eruption of Tambora Volcano in Indonesia. The
eruption of Krakatoa in 1883 had a noticeable effect on the
climate. Measurements of solar radiation being conducted at
the time of the 1912 eruption of Katmai Volcano proved the
effectiveness of volcanic ash to lower the temperature.
Beginning in the 1880s, a world-wide warming trend set
in, which reached a climax in the 1940s, and since that time
has reversed. The role of volcanic dust was examined in an
effort to account for these world-wide temperature changes,
and it was concluded that major volcanic eruptions were
responsible for lowering global temperature. The study was
expanded to include pollution of the atmosphere by carbon
dioxide, smoke, dust particles, etc., largely derived from the
combustion of fossil fuels, petroleum and gas. The results
showed that pollution by human activities was minor
compared to the contribution by volcanoes and that volcanic
dust is an important factor in world-wide temperature
changes.
Periodic ash falls from volcanic eruptions maintains the
fertility of the soil. A study in Indonesia shows a direct
relationship between soil fertility, density of population, and
the location of active volcanoes.
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