Understanding global security - Peter Hough
Understanding global security - Peter Hough
Understanding global security - Peter Hough
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NATURAL THREATS TO SECURITY<br />
The threats to human life from volcanic activity come in many, diverse forms.<br />
Volcanic eruptions<br />
The most familiar threatening image of volcanicity is the sight of molten lava flowing<br />
down the hillside. Today, however, lava flows represent a minor threat to life since<br />
they are generally slow enough and well enough observed to permit the evacuation<br />
of nearby settlements.<br />
Lava flows<br />
Pyroclastic flows<br />
More deadly than lava flows is the movement of mixtures of volcanic gases and debris<br />
that can be formed on the side of a volcano. The Roman city of Pompeii was famously<br />
destroyed in this way and the highest death toll by volcanicity in the twentieth century<br />
was also accounted for in this way when 29,000 people were killed near Mount Pelee,<br />
Martinique in 1902.<br />
Lahars (volcanic mudflows)<br />
Volcanic debris mixed with water can also form a deadly agent, principally since this<br />
moves further and more quickly than lava or pyroclastic flows. The 1985 Nevada del<br />
Ruiz eruption in Colombia killed 23,000 people in this way when a relatively small<br />
eruption produced pyroclasitc flows which mixed with snow at the summit and flowed<br />
many kilometres down the valley, engulfing the town of Armero.<br />
Various solid objects can be spat out at high speed during a volcanic explosion.<br />
Chunks of molten lava chilling in the air to form ‘volcanic bombs’, volcanic glass and<br />
ash may be showered onto residential areas. Eruptions of Mount Pinatubo in the<br />
Philippines in 1991 killed over 200 people, principally as a result of tephra collapsing<br />
the roofs of houses in nearby setlements. Tephra may also create knock-on disasters<br />
by downing aeroplanes, instigating lightning and damaging infrastructure and crops.<br />
A famine occurred following the 1815 Tambora eruption in Indonesia, the largest<br />
and most deadly volcanic eruption in history, killing 82,000 peopole in addition to<br />
the 10,000 direct deaths from tephra and pyroclastic flows (Univ. N. Dakota 2002).<br />
Tephra<br />
Poisonous gases<br />
Many toxic chemicals can be emitted by volcanic eruptions, including carbon<br />
dioxide, carbon monoxide, sulphur dioxide, hydrogen sulphide and gaseous forms<br />
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