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2. Relief
5. GEOLOGICAL HAZARDS
The danger not only comes from the magnitude or intensity of the event, but also
because of the impossibility of knowing in advance when and where they will occur.
The most dangerous geological hazards are volcanoes and earthquakes.
5.1. Volcanoes
Geological hazards
are manifestations of the dynamics of the
forces
of the Earth’s
interior. They can cause
natural disasters
in areas where they occur.
Volcanoes are landforms that are created by the
eruption
of materials from the
deepest
parts of the
Earth’s crust
and the
mantle
.
The temperatures in these areas are extremely high (about 1000 ºC) and the rocks are
molten (melted), called magma. Magma that comes out to the surface is called
lava
.
Volcanoes also eject gas, ash and fragments of rock.
Volcanic bombs
are rocks ejected
from a volcano during an eruption, which cool and solidify when they hit the ground.
The main parts of a volcano are:
❚
Magnetic chamber
:
the area where the magma accumulates.
❚
Chimney
: the opening through which the magma rises inside the volcano.
❚
Crater
: the upper part of the chimney where materials are ejected. In some cases,
there smaller craters that have their own chimneys, next to the main crater.
❚
Volcanic cone
: a raised area around the volcano created by materials ejected
from the volcano. These materials are mainly rocks, ash and lava flows.
Bodies covered with ash in the
streets of Pompeii
One of the most famous
volcanic eruptions occured in
79 A.D., when Mount Vesuvius,
in Italy, erupted and covered
the cities of Pompeii and
Herculaneum with ash. The
inhabitants didn’t even have
time to react, as shown by the
bodies covered by ash, found at
Pompeii. The ashes preserved
the bodies, buildings and tools,
which is why they can still be
seen today.
volcanic cone
magma chamber
crater
Did you know?
chimney
