A Volcanoe has 5 parts. A vent, a crater, a pipe, a cone, and a magma chamber.
A vent is an opening in the earth surface. A crater is a bowl shaped diversion
were lava and ash are released.The pipe is a passageway in the volcano
in which the magma rises through to the surface during an eruption. The
cone is the circular shape around the volcanoe were lava and ash are piled.
Hot
Liqued lava can be very dangerous. People usually have time to get
out of their homes beacuse of how slowly it moves. Ash and firery
Fragments are usually spit up from the earth. The cooled fragments
that fall back to Earth are called tephra.This can cause a great danger
to any one. Evan worse than lava flows! Hot gases and tephra
flow down the mountain.
Volcanoes usually occur on plate boundries. Plate broundries are
where plates meet or split apart. This may cause alot of damage!
There are three type of plate boundries; convergant, divergant, and transformant.
Volcanoes form on Convergant and divergant boundries. They can also form
on hot spots. At a convergant boundry a plate can be pushed under another
and melt to form magma. At a divergant boundry plates are shoved
togehter and magma is pushed to the top.
Mount St. Helens, Washington
Mount St. Helens is at 46.2N and 122.2W. It is 8,363 feet high.
This volcanoe is a stratovolcanoe. That meens it erupts somtimes
and then stays still for a long time. And when it erupts again the explosion
can be huge. On 18 May 1980 the top of Mount St. Helans ,wich was 1,300
ft., was gone in minutes! The explosion sent remains over 150sq
miles away. The sky was coverd in ash and smoke. Mount St.
Helans is a very
powerful volcanoe! You can find out more about Mt. St.Helanshere.
Vesuvius
Situated in the Bay of Naples in Italy this volcanoe is surronded by 3
million people. In 1631, it destroyed Pompeii, a very lage city. Since
this volcanoe erupted so long ago it may be ready to explode any time soon.
That explosion would take away about 1 million people. The public officials
of this area are trying to move some people closest to the mountain to
a safer place before it's to late! They hope to have the place nice
and secure by the year 2002. More about this volcanoe
here.