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Typically, where in the world do natural
hazards occur?
Hydrological Hazards
•Hydrological hazards- (Flooding, drought). Flooding generally occurs
on coastal plains or near rivers/lakes/streams. It happens when there is
heavy rainfall that fills rivers or streams above their normal capacity, or
if there are very high river or coastal tides that could cause levels to
rise or surge. The excess rain water that gathers cannot be restrained
by normal boundaries (such as a river embankment or man made
levees) and follows the path of least resistance.
Drought usually occurs where there is very hot, arid land. Mainly on the
equator in places such as middle Africa and Northern Brazil. It happens
when there in minimal rainfall and if the land is very dry it may not be
able to absorb and therefore it evaporates back into the atmosphere.
Atmospheric Hazards
•
Atmospheric hazards- (Cyclones, hurricanes, snow, fire, fog). Tornadoes occur
in many areas around the world. However, no region experiences more
tornadoes than the central United States. Besides this region, Brazil and
portions of western Europe are perhaps especially at risk. In the British Isles, an
average of 20 tornadoes per year are recorded. Canada receives approximately
13 tornadoes per year. In North America, most tornadoes occur in an area
known as "Tornado Alley", which is the central Great Plains region of the United
States. The states of Kansas and Oklahoma usually experience the most
tornadoes per year.
The Northern Hemisphere usually has about twice the number of tropical
cyclones as the Southern Hemisphere (averaging 55 storms per year vs. 25
storms per year)
Snow is common across most of North America, Europe, and Asia. Between the
months of November and April, latitudes north of 40 degrees N receive an
average of 25 inches (64 cm) of snow or greater.
Wildland fires most commonly occur in southern grasslands
and southern needleleaf forests, where vegetation is
abundant, humidity is usually low, and temperatures are warm
Geological Hazards
•
Geological hazards- (Landslides, sink holes)
Slope failures can be triggered by weather events, geologic events,
human modification of the landscape, or most commonly, some
interaction of all of the above. Therefore, slope failures occur nearly
everywhere slopes exist. Mountainous regions, hilly regions, and
coastlines have the greatest occurrence of slope failures. Also,
locations in active tectonic regions are prone to slope failures
triggered by earthquakes or volcanic activity. Sinkholes form in karst
landscapes, where water has dissolved underlying bedrock, typically
limestone or gypsum. The southeastern United States is particularly
prone to sinkhole formation; over 50% of the state of Kentucky is
subject to these hazards. Along the highways of the Rocky
Mountains and coastal mountain ranges of California, rockfalls
cause transportation delays, vehicle damage, and road damage
every year.
Tectonic Hazards
•
Tectonic Hazards- (Earthquakes and volcanoes). Along the western edge of
North America the oceanic crust is sliding under continental crust (a process
known as subduction). In the world, three regions in particular are at
significant risk of volcanic activity:
The Pacific Rim (which outlines the Pacific Ocean) is also known as the
"Ring of Fire" due to its extensive history of volcanic eruptions. Many
countries around the Rim are at great risk of volcanic eruptions. In the east,
these include Japan, the Philippines, Indonesia, New Guinea, New Zealand,
and many of the South Pacific Islands.
In South America, all west coast countries (Chile, Peru, Ecuador, Columbia)
lie in the shadow of the explosive Andean Mountain Range volcanoes. The
Mediterranean and Middle East regions including the countries of Italy,
Greece, Turkey, Iran, Saudi Arabia, Yemen, and Pakistan have had a
enormous amount of volcanic activity throughout history.
Also the Great Rift Valley in eastern Africa has many volcanoes found in the
countries of Ethiopia and Kenya.
Tectonic Hazards ctn’d....
•
In the last century, over 4600 earthquakes have been recorded along the
western coast of North America. The western states, including California,
Oregon, Washington, British Columbia, Yukon Territory, and Alaska are all
prone to earthquakes. Baja California and western Mexico also have many
earthquakes. The Pacific Rim (which outlines the Pacific Ocean) records
more earthquakes than anywhere else on Earth. In the east, this includes
the countries of Japan, the Philippines, Indonesia, New Guinea and New
Zealand. In South America, all west coast countries (Chile, Peru, Ecuador,
Columbia) are at risk. The Mediterranean and Middle East regions including
the countries of Italy, Greece, Turkey, Iran, and Pakistan have been plagued
by substantial numbers of earthquakes.