Global Hazard Patterns

earthquakes, land-slides, hydro-metrological events, diseaster hotspots, philippines diseasters

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  • Created by: harry
  • Created on: 18-12-09 12:58
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Global Hazard Patterns
The three main geophysical hazards are earthquakes, volcanoes and tsunamis.
Earthquakes:
Main earthquake zones are clustered along plate boundaries.
Our earth crust is divided into seven major sections or plates, and a number of smaller ones. Some
are oceanic and some are continental. The plates float on the underlying semi-molten mantle,
(asthenoshere).
There are three major types of plate boundary, constructive destructive and conservative.
(Constructive and destructive = most powerful)
Hotspots from within the asthenosphere generate thermal convection currents which cause magma
to rise towards the Earth's surface. This process forms new crust along the line of constructive
boundaries, where plates are diverging.
At the same time old crust is being destroyed at destructive boundaries, where plates converge. The
type of activity demands on the type of plates which are meeting.
At constructive boundaries, two plates slide past each other and there is no creation or destruction
of crust.
The type of movement and degree of activity at the plate margin almost totally controls the
distribution, frequency and magnitude of eruptions.

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Conservative boundary: a boundary between plate where the movement of the plates is parallel to
the plate margin and the plates slide past each other. Produces frequent, shallow earthquakes,
sometimes of high magnitude.
Constructive boundary: a boundary between plates where the plates are diverging or moving apart.
Associated with large numbers of shallow, low-magnitude earthquakes as magma rises.
Destructive boundary: a boundary between plates where the plates are converging (moving
together).…read more

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Snow avalanches:
Concentrated in high mountainous areas
Suggestions that global warming may be increasing avalanche occurrences
The distribution of hydro-meteorological hazards
Widespread in distribution, growing in frequency and increasingly unpredictable in their
location.
Drought:
Over one third of the world's land surface has some level of drought exposure. This includes
70% of the world's people and agricultural value, which means the drought, has an effect on
global-food security.…read more

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Flooding hazards: deaths by drowning and disease, destruction of food crops and
infrastructure and loss of homes. In developed countries it disrupts transport and
infrastructure, damages livelihoods and created high insurance costs.
Storms
Include tropical cyclones, mid-latitude storms and tornados.
o Tropical cyclones are violent storms between 200 and 700 Km in diameter. They
occur in latitude 5-20 degrees north and south of the equator.…read more

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The Philippines-disaster
The group of island in the Pacific Ocean are located in a natural disaster hotspot, characterised by a
high vulnerability to natural hazards.
On average, the islands have 19 to 21 cyclones every year.
Cyclonic activity not only exposes the nation to intense rainfall and strong winds, it also
heightens the risk of localised flooding and landslides.
The region is subject to the El Niño Southern oscillation that exists within the Pacific Ocean
and causes cyclical drought and flood.…read more

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