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NATURAL HAZARDS AND DISASTERS
Unit III – Chapter 4
WHAT ARE THEY?
Floods Earthquakes Hurricanes Tornadoes Volcanoes Tsunamis Avalanches
WHAT IS A NATURAL HAZARD?
Aspects of physical world that have potential to cause considerable harm to people
o a dormant volcano
WHAT IS A NATURAL DISASTER?
When a natural hazard is activated and reacts in such a way as humans and/or communities are destroyed
WHY ARE NATURAL DISASTERS TAKING A HEAVIER TOLL THESE DAYS?
Occur most often in heavily populated areas in southern hemisphere
Poorer countries with less solid infrastructure
More difficult for poorer countries (LCD and LLCD) to react quickly and compensate for loss
FACTORS USED TO C0MPARE NATURAL DISASTERS
Frequency How often a particular event is likely to occur
Duration How long an event will last
Extent How large an area or region will it effect widespread or restricted to a small area
Speed of onset How much warning will you get
Spatial dispersion Area affected by disaster – prediction of
where it will take place
Temporal spacing How hazards occur in time – hurricanes
occur in the same areas at the same time of year; while volcanoes are unpredictable
CLASSIFYING NATURAL DISASTERS
Loss of life Number of injuries Damage to property Intensity/strength of event
wind speed, Richter scale for earthquakes
Event causes other hazards – atmospheric, biologic and geologic
WHAT IS A GLOBAL HAZARD?
An event that affects people in many areas of the world
An event that has long term effects (for many years)
An event that causes permanent damage or serious contamination of the natural environment
TYPES OF NATURAL DISASTERS
Atmospheric Biological Geological
ATMOSPHERIC NATURAL DISASTERS
TYPES OF ATMOSPHERE HAZARDS/DISASTERS
Severe storm Cyclonic storm – hurricane, cyclone,
typhoon Tornado Flooding Drought Wildfire
CYCLONIC STORMS Connected with weather and climate changes normal weather patterns develop because of
differences in air masses Prevailing winds shift these air masses When two air masses collide a sharp boundary
called a front forms Rotating low pressure areas, or cells form along
storm front Depending on how different the air masses are
influences the types of storm that will develop
TROPICAL CYCLONES
Develop as the result of high temperatures and large amounts of water vapour
Develop over oceans and follow curved storm paths
Moved by prevailing winds and the Coriolis effect
Usually hit land where they cause significant destruction
THE HURRICANE
TORNADO formation of a tornado - Bing Video
HURRICANE VS TORNADO
Form over water Called hurricanes -
Atlantic; cyclones – Indian; typhoons – Pacific
Most destructive of all natural disasters
Follow curved storm paths and often end up over land
Cover extensive areas High winds, rain Extensive area so more
widespread damage
Form over land Called twisters, funnel
clouds Occur mostly in middle
latitudes with thunderstorms that are part of cyclonic storm forming on cold front
Narrow path High winds, rain Limited area so less
widespread damage
FLOODS AND FLOODING
High precipitation associated with a storm front
Rivers rise, overflow and flood adjoining lowland
Storms can cause “storm surge” which cause extensive lowland flooding
Storms can also cause mudslides
DROUGHT
Extended periods without rainfall Prolonged drought – crop failure, death i.e. Sahel area of sub-Saharan region of
Africa Desertification = productive dry land is
degraded to the point where it is no longer productive
WILDFIRE
Dry weather conditions, high winds, large forests are ideal conditions for wildfires
BIOLOGIC NATURAL HAZARDS AND DISASTERS
Millions of deaths attributed to infectious or parasitic diseases
MEASLES
Prior to 2000 – 1.2 million children died/year (textbook)
In 2008 - 164 000 measles deaths globally – nearly 450 deaths/day or 18 deaths/hour
Measles vaccination (up 72% from 2000) resulted in a 78% drop in measles deaths between 2000 and 2008 worldwide
LDCs and LLDCs – 95% of deaths
HIV
By the end of 2008 - 33.4 million people worldwide were living with HIV
2 million people died of AIDS-related illnesses.
Globally, less than 1 in 5 at risk of HIV has access to basic HIV prevention services.
Only 36% of people who needed HIV treatment had access to it by end of 2009
2010 report – significant progress is being made
HIV/AIDS progress report from 144 low- and middle-income countries in 2009: 15 countries, including Botswana, Guyana
and South Africa, were able to treat more than 80% of HIV-positive pregnant women
14 countries, including Brazil, Namibia and Ukraine, provided HIV treatment to more than 80% of HIV-positive children
8 countries, including Cambodia, Cuba and Rwanda, have achieved universal access to antiretroviral treatment (ART) for adults.
RIVER BLINDNESS
35 million people world-wide suffer from disease 140 million African people are at risk caused by a parasitical worm, onchocerca
volvulus. The worm larvae are spread by the black simulium
fly, which breeds in the high-oxygen water of fast-flowing rivers.
fly transmits disease when it bites people, making those who live or work near the rivers vulnerable.
Treatment - Mectizan®.
Ways to break the cycle of infection: reducing # of flies by spraying affected areas with
insecticide slowing fast-flowing rivers, making them unattractive
as breeding grounds reducing exposure to flies by using protective garments killing the adult worms by removing the worm 'nodules'
- difficult because infected villages are often very remote and poor, making accessible surgery difficult.
providing a yearly dose of the drug Mectizan® in affected areas.
Problems with medication Needs to be administered regularly and communally
GEOLOGIC HAZARDS AND DISTASTERS
EARTHQUAKES
Most violent and sudden Cause the highest # of deaths July 27, 1976 – Tangshan China – killed
255,000 + 665,000 injured Occur in areas of world defined by
tectonic plates Many run through highly populated
areas
AFTER EFFECTS
Collapsing buildings Breaks in communication and
transportation Electricity loss Fire Flooding Disease
MORE SEVERE EFFECTS IN LDCS AND LLDCS
High population density Substandard housing Lack relief resources
VOLCANOES
Cause fewer deaths than any other natural disaster
Slow – lots of warning Well known volcanoes – Mt. Vesuvius
(Pompeii), Mt. St. Helens (Washington State), Eyjafjallajökull (Iceland)
Hawaii has daily volcanic activity Iceland has harnessed geothermal energy
for heating and electricity generation
SLIDES AND AVALANCHES
Slide is rapid movement down a slope – rocks, soil or combination
Combination of geological factors + triggering event like heavy rain or earthquake or human effect – deforestation, clearcutting
Avalanches – rapid movement of snow and ice
TSUNAMIS
Japanese for “harbour wave” Not connected to tides – therefore not
“tidal waves” Caused by mudflows, landslides,
earthquakes or volcanoes that take place on ocean floor
Most common cause – earthquakes Devastating tsunami – Thailand,
Christmas 2004 – 230,000 deaths
THE ROLE OF HUMANS IN NATURAL DISASTERS
We are victims of natural disasters We can also cause them to be more
disastrous Clear cutting, hillside farming, urban
development
REFERENCES
http://visual.merriam-webster.com/images/plants-gardening/plants/plant/photosynthesis.jpg, retrieved March 1, 2010
http://www.allaboutgemstones.com/rock_cycle.html retrieved March 3, 2010
http://en.wikipedia.org/wiki/Earth March 3 http://www.bing.com/images/search?q=Tide&FORM=BIFD#focal
=c753352f665971332d781ca13addc07e&furl=http%3A%2F%2Flibrary.thinkquest.org%2FC003124%2Fimages%2Ftides.jpg March 3
http://www.harcourtschool.com/activity/science_up_close/314/deploy/interface.html March 3
file:///H:\My%20Pictures\Hurricane_formation.gif retrieved March 11
file:///H:\My%20Pictures\flappy_tornado_formation.jpg retrieved March 11
National Geographic websites