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olcano 
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What
is A Volcano?
Extremely
high pressure and heat melt the rock under the earth. It then rises
to the top till it is just under the earths crust. Gasses and the
magma build up pressure until the crust can no longer hold the pressure.
It then erupts. Volcano's can occur at either plate boundaries or
hot spots on the bottom of the ocean floor such as Hawaii.
What
can a volcano do?
Eruptions
send ash and lava flying into the sky. Sometimes they can block out
the sky for days and weeks. Other volcanoes ooze out of the earth slowly
and steadily. Volcanoes or hot spots under water can build up rock
that has cooled and create islands, Like Iceland. Volcanoes that
are found near communities can become very dangerous.
What kinds of volcanoes are
there?
Shield Volcanoes such as Hawaii, ooze slowly out and spread to very far
distances. Strato volcanoes like Mt. St. Helens are like mountains
and they build up pressure by means of gasses and then they erupt violently.
Rhyolite caldera complexes are the most explosive of volcanoes, so they
usually end up collapsing upon themselves. Monogenetic feilds are
a feild of vents and flows constantly flowing and oozing. And their
are mid-ocean ridges which cause hot spots which can form new islands.
The hazards of Volcanoes
Their
are many kinds of hazards caused by earthquakes such as Volcanic
Earthquakes
which are tremors caused by volcanoes.
There are Blasts
which
is all the smoke, ash and lava sent out by the volcanoes eruption.When
a volcano erupts it will sometimes eject material such as rock fragments
into the atmosphere. This
material is known as Tephra.
The eruption can release Volcanic
Gasses such as hydrogen and Carbon Monoxide.Lava
Flows are the least hazardous of all processes
in volcanic eruptions. How far a lava flow travels depends on the flows
temperature, silica content, extrusion rate, and slope of the land.
Volcanic structural collapse in the form of Volcanic structural collapse
in the form of Debris
Avalanches, Landslides, and Tsunamiscan be almost
any size ranging from a few loose rocks falling from the crater rim of
a volcano to large avalanches.
Deep within the Earth it is so hot that some rocks
slowly melt and become a thick flowing
substance called magma. Because it is lighter
than the solid rock around it, magma rises and collects in magma
chambers. Eventually some of the magma pushes
through vents and fissures in the Earth's surface. A volcanic
eruption
occurs! Magma that has erupted is called lava. Most volcanoes provide various
types of warnings
before eruptions begin. Although an explosiveeruption could occur without
warning, some premonitory events more likely will precede the next eruption.Steam-blast
eruptions could occur with little or no warning as superheated water flashes
to steam; magmatic
eruptions, however, involve rise of magma toward
the surface. Such an upward movement of magma normally will
generate detectable earthquakes, may deform the
ground surface, and may cause anomalous heat flow or changes in the temperature
and chemistry of the ground and spring waters.
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