2. What’s a volcano?
A volcano is an opening in the earth’s
crust through which lava, volcanic ash,
and gases escape. Volcanic eruptions are
partly driven by pressure from dissolved
gas, much as escaping gases force the
cork out of a bottle of champagne.
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3. How is a volcano formed
Volcanoes are formed by the movement and interaction of tectonic plates beneath the
Earth's surface. When two tectonic plates collide or move apart, magma (molten rock) from
the Earth's mantle can rise to the surface through a vent or fissure, resulting in a volcanic
eruption.
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4. PARTS OF THE VOLCANO
Magma is the molten rock that is
located beneath the surface of the
Earth. Once it reaches the surface it
is now called lava. The magma
chamber is the source of magma of
a volcano. The vents of the volcano
are the channels where magma can
move from underground. The main
vent is the largest vent that leads to
the crater and supplies the most
magma while the secondary vents
are smaller vents carrying small
amounts of magma.
The crater is the opening of the volcano where the most of the molten rock, ashes, and steam
comes out during a volcanic eruption. The slope of the volcano is made of layers of lava and ash.
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5. A volcano is considered as active is it has erupted within
the last 10,000 years. There could only be more than 500
active volcanoes on Earth.
Extinct volcano is considered extinct if it has not erupted
in historical times. However, there are volcanoes that have
long been thought to be extinct but suddenly resumed
eruption lately. Example is the Four-peaked Volcano in
Alaska, which has been considered extinct for 10,000
years but erupted in the year 2006. In this case, the term
dormant or inactive is more applicable than extinct. An
example of an inactive volcano is Mt. Batulao in
Batangas. It has not erupted for more than 10, 000 years.
Based on frequency of eruption
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6. What scientists consider as extinct are only
those that are not likely to erupt again because
their supply of magma has been depleted. The
question is, how sure are we that a volcano has
no more magma supply?
And so, scientists now prefer the terms active
and inactive only, being most cautious with the
term extinct. The term active is used when the
volcano shows signs of activity like earthquakes
and gas emissions.
Based on frequency of eruption
7. Types of volcano
There are three basic types of volcanoes: shield volcanoes,
cinder cone volcanoes, and composite volcanoes.
MAGMA CHAMBER
CENTRAL
VENT
MAGMA CHAMBER
CENTRAL
VENT
MAGMA CHAMBER
CENTRAL
VENT
SIDE VENT
CRATER
Cinder cone volcano Composite volcano Shield volcano
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8. Cinder cone
Cinder cone volcanoes are usually small. They are made up of pyroclasts or
fragments of volcanic rocks that form steep slopes around their wide crater.
They often form in groups near a large volcano. Most of them erupt only
once.
CENTRAL
VENT
MAGMA CHAMBER
CRATER
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9. Composite volcano
Composite volcano or stratovolcano is a tall mountain with a crater on top from which
pyroclastic (or “fire-broken) materials, gases, and lava escape. It is in fact the most
common type of volcano. Its height is explained by the volcanic materials that eventually
cool and harden after eruption, piling on top of another with subsequent eruptions. Its
magma has a high content of silica, making the lava thick or viscous and capable of
reaching great heights. Some of the composite volcanoes are known for their violent
eruptions.
CENTRAL
VENT
SIDE VENT
CRATER
MAGMA CHAMBER
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10. Shield volcano
Shield Volcano is quite different from composite volcano because it is almost flat and
broad like a warrior’s shield. Its magma has a lower percentage of silica and is thus less
viscous than that of a composite volcano. During an eruption, its lava flows easily and
reaches a great distance from the crater. Mauna Loa, Kilauea, and other Hawaiian
volcanoes are shield volcanoes. As of today, there are no shield volcanoes discovered in
the Philippines. This might be because of the viscosity of the magma in the Philippines.
MAGMA CHAMBER
CENTRAL
VENT
SIDE VENT
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11. Examples of volcanoes
Mayon volcano Kilauea volcano paricutin
Known for its perfect cone shape
and is an example of a
stratovolcano or composite
volcano.
Kīlauea is an active shield volcano
in the Hawaiian Islands. It is an
example of shield volcano.
Paricutin is a cinder cone volcano
in Michoacán,
Mexico. Paricutin was named one
of the seven natural wonders as an
active volcano.
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12. Pacific Ring of fire
is a path along the Pacific
Ocean characterized by
active volcanoes and
frequent earthquakes.
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13. Effects on human health
Volcanic eruptions can release a variety of gases and particles, including ash, sulfur
dioxide, carbon monoxide, and hydrogen sulfide, which can have serious impacts on human
health.
Volcanic ash is composed of small, sharp particles that can
irritate the eyes, nose, and throat, and can also cause
respiratory problems such as coughing, bronchitis, and
asthma. In addition, volcanic gases can cause short-term
health effects such as headaches, dizziness, and nausea, and
long-term exposure can lead to chronic respiratory conditions,
heart disease, and other health problems.
14. “a lung disease caused by inhalation of
very fine silica dust usually found in
volcanoes"
Pneumonoultramicroscopicsilicovolcanoconiosis
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