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Geography
Volcanoes
The earth has three layers: the crust (at the top), the mantle
(in the middle) and the core (at the bottom and closest to the
centre of the earth).
core
The crust is very thin and it consists of large, thin pieces of
rock, called plates. These plates are constantly moving, and
they lie on the hotter, softer material under them, called the
mantle.
There are 16 main plates. Volcanoes usually form when the
plates push against or pull away from each other. When this
happens, one plate slides ‘under’ the other one. The plate
melts and forms a hot liquid called magma.
The heat inside the earth causes a lot of pressure. Because
the plates are always moving, holes or cracks sometimes
form in the crust. If there is a lot of pressure, the hot liquid
magma will explode through the cracks. This explosion is
called a volcanic eruption. When magma comes out of the
earth, it is called lava. The temperature of lava can be
700° – 1,200° C.
Volcanoes are mountains. They form over thousands of years.
They can be different shapes, but inside they are all the
same.
The magma chamber (the area at the bottom that is full
of magma) has a tube or pipe leading from it up to the top
of the volcano. The magma escapes out of the earth’s crust
through the opening at the top, called the vent.
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crust
mantle
We can divide volcanoes into three groups, according to
their phase of activity.
t t he active phase An active volcano erupts regularly,
or has erupted recently.
t the dormant phase A dormant volcano has not erupted
for many years, but there is still some activity inside it,
and future eruptions are possible.
t the extinct phase Scientists do not think that these
volcanoes will ever erupt again, because there is no
more lava inside the volcano.
There are more than 1,500 active volcanoes on earth. The
largest one is Mauna Loa in Hawaii. Its lowest part is at the
bottom of the sea. From the bottom to the top, it is about
8,700 metres tall, taller than Mount Everest.
lava magma chamber pipe vent
Glossary
layer strato
rock roccia
slide (v) scivolare
melt fondersi
pressure pressione
crack (n) incrinatura,
fenditura
explode esplodere
phase fase
regularly
frequentemente
1
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What is the difference between…?
the earth’s crust and the earth’s core
lava
2
The crust is the top and the core is the
centre.
1 magma and lava
3
2 the pipe and the vent of a volcano
3 a dormant volcano and an extinct volcano
Vesuvius
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Vesuvius
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Is Mount Vesuvius an extinct volcano?
No, it’s a dormant volcano.
1 How many times did it erupt in the 20th
century?
2 When was its last eruption?
3 When was Pompeii destroyed?
4 What damage did Vesuvius’s last eruption
cause?
Presentazione orale
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Cerca le seguenti informazioni
sull’Etna e completa il factfile.
Mount Vesuvius, near Naples, is now a dormant
volcano, but has erupted in the last 100 years.
It erupted in 1906, 1929 and 1944, but its most
famous eruption was in AD 79. On 24th and 25th
August that year, when Vesuvius erupted, 2,000
people died in the Roman towns of Pompeii
and Herculaneum. There were two phases of
the eruption. In the first phase, ash and rocks
covered the towns. Then a cloud of gas, ash and
rock poured down the side of the mountain. The
temperature of the cloud was 350°C, so it killed
everyone in its way. When Vesuvius last erupted,
in 1944, there was just a flow of lava. No one
died but the volcano destroyed the towns of San
Sebastiano and Massa.
Location:
Height:
m
Active / dormant / extinct?:
Date of first known eruption:
Date of most destructive eruption:
Damage from this eruption:
Date of last eruption:
Damage from last eruption:
Glossary
mainland
continentale
ash cenere
cover (v) ricoprire
side fianco
flow (n) flusso
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