Download Getting to Know: Effects of Volcanoes

Getting to Know: Effects of
Volcanoes
Did you see photographs of the 2010 eruption of
the volcano Eyjafjallajökull in Iceland? It spewed
a great deal of ash into the air, causing travel
disruptions and polluting the atmosphere across
Europe. You may have also seen footage of the
violent eruptions of Mt. St. Helens, which caused
severe destruction in Washington State in 1980.
People often imagine that all volcanic reactions
involve the spewing of huge amounts of red-hot
lava and ash into the air, but in reality, volcanic
eruptions and their effects on Earth’s surface
features can vary greatly.
This is how Mt. St. Helens looks today.
Notice the large crater caused by the
1980 eruption.
Misconception 1: Are all volcanic eruptions as dramatic and destructive?
When Mt. St. Helens erupted, an enormous area was buried in ash and debris. Such
explosive volcanic eruptions, however, are rare. It is more common for volcanoes to
remain quietly active over long periods of time, releasing small amounts of steam, ash,
and lava now and then. Mt. Kilauea on the Big Island of Hawaii, for example, has been
active for almost 30 years!
How can volcanoes affect Earth’s surface?
If a volcanic eruption is explosive, part or all
of the volcano may blow up. For example, the
Mt. St. Helens eruption left a huge crater in the side
of the mountain. The mountain today looks much
different than it did before the 1980 eruption.
In contrast, a constructive eruption is one that helps
build mountains or islands. In the Hawaiian Islands,
for example, the lava from the volcanoes flows until
it reaches the sea. When it hits the water, it cools
and forms rock. Over time, the new rock makes the
islands bigger as the shoreline keeps extending
outward. In fact, the Hawaiian island chain formed
as a result of volcanic activity.
Cooled lava changes the shape of
landforms.
Concept: Effects of Volcanoes
Getting to Know
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How can volcanic eruptions affect Earth’s ecosystems and
atmosphere?
Volcanic eruptions can harm ecosystems and habitats in several ways. The lava and ash
released by a volcano can kill or displace organisms. Volcanoes also have giant flows of
gas and rock called pyroclastic flows. Pyroclastic flows can be extremely hot and can cause
wildfires that destroy habitat. Another type of flow, called a lahar, is a giant mud and debris
flow. Lahars can wipe out everything in their paths. Volcanoes in cold regions can also melt
snow and glaciers, causing flooding. All of these effects can harm the ecosystems around the
volcano.
Volcanoes can also impact Earth’s atmosphere. When a large plume of ash enters the
atmosphere, it can block sunlight from reaching Earth’s surface. This can cause global
temperatures to drop and affect climate. Volcanic eruptions can also release carbon dioxide,
which is a greenhouse gas. If too much carbon dioxide builds up in the atmosphere, it can
cause changes in Earth’s climate.
Misconception 2: If a volcano doesn’t discharge lava, it’s not as dangerous, right?
Wildfires, floods, and mud flows can be just as destructive as flowing lava. In additon,
the ash discharged from a volcano is extremely hot, just like lava, and is expelled very
quickly from below Earth’s surface. It can enter Earth’s atmosphere and be carried
great distances by wind currents. Volcanic ash can coat the leaves of plants, making
it impossible for them to take in light or carbon dioxide, and it can enter the lungs of
animals, making it difficult for them to breathe properly.
What are the positive effects of volcanic eruptions?
It’s true that volcanoes can inflict a lot of damage,
but they can have some positive effects, too. The
ash that spews from volcanoes can help enrich
the soil. Some volcanic ash mixed into the soil can
help plants grow and thrive. In fact, volcanic soils
are some of the most fertile agricultural land in
the world. This soil, in combination with the ideal
climate of the islands, supports Hawaii’s production
of pineapple, coffee, and other valuable crops.
A volcanic eruption can spew dangerous
ash into the atmosphere.
Concept: Effects of Volcanoes
Getting to Know
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Volcanoes are an important feature of Earth’s
surface. Let’s learn more about how volcanoes affect
the creation of landforms and other aspects of the
environment.
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© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.