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Volcanoes erupt when the pressure within the magma under the
sudace
becomes
stronger than the
rocks
that make
up the
volcano. That pressure comes
both from
the buoyancy
of
the magma and from gas bubbles inside the magma that want
to expand. lf the pressure can be released easily then you will have a peaceful
eruption such as in Hawaii. lf the pressure is released explosively then
you
have
a
dangerous eruption such
as pinatubo,El chichon, or Mt.st.
Helens.
Step
1:
Molten rocks, or magma,beneath the earth's
surface rise due
to high pressure.
Step
2: Magma pushes itself upwards through the
cracks
in
the
ear1h.
Step 3: Lava erupts from
a
volcano.
Step
4: Lava cools down and builds
up
outside the
volcano.
Step
5:A
mountain forms.
The fierce volcano eruption may swallow and even destroy
the
large
tracts of
land, burning
a
great number of lives and properly into ash. in
the meantime,
the
ash that the volcano has spouted
is
the best
natural lertilizer.
For
example, the
mulberry tree grows
up
very well in Fuji Mountain and
it is good
for
sericulture;
Grapes are
rich and
fruitful
in
the vesuvius volcano area. Further more, the
landscape
in
the volcano area
is
quite peculiar, which makes
it
become
a
tourist
attraction.
-5-
:,
The hazard and benefit
of
a
volcano
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