The Science of Natural Disasters
, 7th ed., by Patrick L. Abbott (New York: McGraw-Hill, 2009;
QUESTION 42 volcanic action
The potential effects volcanoes have on climate can be long and short term as carbon dioxide
and sulfur dioxide are emitted into the air for sometimes short and longer periods of time even
extending to hundreds of years. Sulfur dioxide molecules turn to aerosols high in the
stratosphere, creating a white haze that reflects sunlight. Reducing photosynthesis to plants, thus
reducing the carbon cycle. The white haze reflecting sunlight, is volcanic material thrown into the
stratosphere, as it blocks the sun it also decreases the temperature over the area until it
dissipates. The effect can be less heat and a drop in climatic temperatures, although the aerosols
breaks down and dissipate over a time-scale measured in months. The immediate effects include
When Laki erupted in 1783 it devastated livestock and incurred famine, across Europe the
following winter was unusually harsh and the summer unusually cold. Volcanoes are frequently
mentioned as a driver for long-term global warming, because they emit the greenhouse gas
carbon dioxide, although not as much as human industry.
In the early 1980’s (Mt. St. Helen, Mt. Hekla, El Chichon) there were several volcanic eruptions
adding large quantities of material in the stratosphere. The only eruption that has confused and
bewildered scientists, is the 1991 Mt. Pinatubo eruption. Where the eruption actually cool the
global warming process.
An active volcano can trigger many events; mudslides releasing an icy cover, rock fall,
earthquakes, mudslides, and landslides along with countless other triggers.
In Colombia, the
town of Almero felt mudflow slurries, wiping the town from the face of the earth, killing 25,000
people with only 3,000 survivors.
Volcanoes lie dormant for centuries collecting matter on top and around them. While inactive they
are a beautiful piece of landscape, when explosive their debris succumbs to gravity sending
particles high into the atmosphere.
Rivers since the beginning of time have been a freshwater supply providing food, transportation
and recreation. Collecting excess water from snow and rainfall (surface runoff), flowing toward a
larger body of water or ocean. Nourishing wildlife and plant species within and along its borders.
Providing a constant freshwater supply, irrigation and hydropower using fast flowing rivers and
waterfalls, generating power to many. The riverbed’s gradient and the velocity of current often
times determine the productivity of the river. Increased current increases the oxygen content of
the freshwater, providing for plant and marine ecosystem development. A concave or steeper
riverbed bottom is said to have a higher gradient. Whereas a flat bottom riverbed has a lower
gradient, often found at the mouth of the stream. The less the gradient the closer the river is to