Powerpoint on Volcanoes

2. What are volcanoes ?
A volcano is a mountain that opens downward to a
pool of molten rock below the surface of the earth.
When pressure builds up, eruptions occur. Gases and
rock shoot up through the opening and spill over or
fill the air with lava fragments. Eruptions can cause
lateral blasts, lava flows, hot ash flows, mudslides,
avalanches, falling ash and floods. Volcano eruptions
have been known to knock down entire forests. An
erupting volcano can trigger tsunamis, flash floods,
earthquakes, mudflows and rockfalls.

3. Amazing Facts
The word volcano originally comes from the
name of the Roman god of fire, Vulcan.
Hot liquid rock under the Earth’s surface is
known as magma, it is called lava after it
comes out of a volcano.
There are also volcanoes found on the ocean
floor and even under icecaps, such as those
found in Iceland.

4. More Amazing Facts
While we certainly have some big
volcanoes here on Earth, the biggest
known volcano in our solar system is
actually on Mars. Its name is Olympus
Mons and it measures a whooping 600km
(373 miles) wide and 21km (13 miles) high.
The object with the most volcanic activity in
our solar system is Io, one of Jupiter’s
moons. Covered in volcanoes, its surface is
constantly changing due to the large
amount of volcanic activity.

5. How volcanoes affect peoples lives.
Volcanoes cause ashfall which if falling heavily can
mean people can't breathe. Lava flows are to slow to
run people over but certainly run over houses, roads
and other structures. Pyroclastic flows, a mixture of
hot gas and ash, travel very quickly down the side of
volcanoes. They are so hot and choking that if you got
caught in one it will almost certainly kill you. They
travel between 100-200 km/h that you cannot outrun
them.

6. Volcanic ash is dangerous for people to breathe, as
it is hot and filled with toxic chemicals. As ash
piles up on houses and other structures, the
weight of it can cause those buildings to collapse.
Because lava moves slowly, it generally does not
pose immediate danger to people but is often
extremely destructive to buildings and fields. A
pyroclastic flow is a rush of hot air and ash that
sometimes sweeps down from an erupting
volcano to engulf anything in its path; people in
the way of a pyroclastic flow will be killed.