Volcanoes can occur all around the world. Where the plate boundaries
meet, there will most likely be a volcano somewhere on the fault line.
Volcanoes form on convergent boundaries by the process of one plate going
under the other plate, the first plate melts, and the magma is forces up
causing pressure to build up, resulting in a volcano. Volcanoes form
on divergent boundaries by the process of two plates pulling apart and
creating an opening that fills with magma and builds up and up like that
until it becomes a volcanic island. Volcanoes can form on hot spots
too. The plate moves over a hot spot and melts, "floats" up and causes
a volcano. When the plate moves past the hot spot, it becomes dormant,
or non erupting.
There are three main types of volcanoes. One of them is a composite
volcano also known as the strato volcano. Composite volcanoes are
made up of alternating layers of lava and rock fragments. They are
usually about 2,500 m in height, 1,000 sq. km in surface, and 400 km cubed
in volume. Composite volcanoes erupt in explosive ways. Some
examples of composite volcanoes are Mt. Shasta, Mt. Hood, Mt. Rainier,
Mt. Fuji, and Mt. Mayon. Another type of volcano is the shield volcano.
Shield volcanoes are broad, gently sloping volcanoes made up of many layers
of runny lava. The lava in shield volcanoes is basaltic lava. They
normally are found near hot spots and have low explosive eruptions.
Some examples of shield volcanoes are Mauna Loa and Kilauea. The
last type of volcano is the cinder cone volcano. Cinder cone volcanoes
are the most common. They are steep and made up of lava fragments.
They are usually 250 m in height and 500 m in diameter. An example
of a cinder cone is Paricutin.
One volcano that erupted is Hosho
in Asia. Its location is 33.1N latitude and 131.2E longitude.
Its elevation is 1,788 m. The last time Hosho erupted is October
12, 1995. This is a composite volcano.
Another volcano is Arenal
in North America. Its location is 10.46N latitude and 84.7W longitude.
Its elevation is 1,657 m. The last time Arenal erupted was August
23, 2000. This is a composite volcano.
Volcanoes have quite a few hazards.
One is lava flows. The lava is usually slow enough for people to
get out of the way, but burns everything in its path. Another hazard
is ash. Pieces of ash are pieces of lava that covers a lot of area
and starts fire. Another hazard is pynoclastic flows. They
are hot gas and tephra that come at high speeds and destroys everything
in its path. Another hazard is mud/debris. They happen when
a volcano collapses and burns everything in its way. Other hazard
include tsunamis, volcanic earthquakes, tremors, suffocating gases, and
climate changes.
Some signs before a volcano erupts is that the magma inside of it will rise. Noticeable tremors occur before an eruption too. The ground will appear deformed because of the pressure building up to the eruption. There also is a heat flow. The heat flow causes a change in the temperature of the ground and spring water around the volcano.
The cause
of a volcano is that the magma chambers inside the volcano fill up and
overflow. The magma is lighter than the rocks around it so it is
put on top of the rock in the magma chambers. If the magma is sticky,
the gases build up and then break through the lava. This is an explosive
eruption. If the magma is runny, gases don't build up and the magma
just overflows from the volcano.
