Natural Hazards

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Natural HazardsNatural Hazards

[email protected] on line at: www.geophysik.uni-muenchen.de/~malservisi/classes/NaturalHazards.htm

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NATURAL HAZARDS ??

A natural process that poses a threat A natural process that poses a threat to human life or propertyto human life or property

List of Natural Hazards on whiteboard

Geological Climatical Biological

•Earthquake•Volcanoes•Tsunami•Mass movement•Extraterrestrial impact

•Extreme Weather•Flood•Ocean Waves•Drought•Fires

•Diseases•Plant diseases

Natural Hazards Global EffectsAll these events can have a big impact both socially and economically on the affect societies and environment. Many times they have a global effects.

Some of global effects can be extreme:

Cretaceous Extinction: Asteroid impact and Volcanism; 85% of all species died in the End-Cretaceous (K-T, 65 million years ago) extinction.

Permian Mass Extinction: Cause not really know but probably associated with Climate Fluctuation, Glaciations of Gondwana and formation of Pangaea, or Volcanic Activity. 95% of marine species became extinct!!



Natural Hazards Global Effects

Examples of global effect:

Toba (Sumatra, Indonesia)

eruption ~75000 years ago.

Probably 5C global average

decrease in temperature

(combined with ice age).

Population of Homo Sapiens

From >100000 to <2000

Genetic bottleneck

Natural Hazards Global EffectsAll these events can have a big impact both socially and economically on the affect societies and environment. Many times they have a global effects.

Some of global effects can be extreme:

Cretaceous Extinction: Asteroid impact and Volcanism; 85% of all species died in the End-Cretaceous (K-T, 65 million years ago) extinction.

Permian Mass Extinction: Cause not really know but probably associated with Climate Fluctuation, Glaciations of Gondwana and formation of Pangaea, or Volcanic Activity. 95% of marine species became extinct!!





Toba (Sumatra, Indonesia)

eruption ~75000 years ago.

Probably 5C global average

decrease in temperature

(combined with ice age).

Population of Homo Sapiens

From >100000 to <2000

Genetic bottleneck



Laki (Iceland) eruption 1783: 75% of livestock in Iceland died; 25% of the Iceland population died for the following famine; fluorine poisoning of animals as far away as Britain; ~1.5C diminution of the average year temperature in US and Europe (France Revolution??)



•Santorini eruption+tsunami 1645 BC: Destruction of the Minonian culture (legend of Atlantis?)

•Tambora, Indonesia 1815, average decrease of temperature in northern hemisphere ~0.7C; 1816 “year without summer” (snow in July in Washington DC).

•ChiChi Earthquake, Taiwan 1999:

prices of computers chips double worldwide for few months

Geological Climatical Biological

•Earthquake•Volcanoes•Tsunami•Mass movement•Extraterrestrial impact

•Extreme Weather•Flood•Ocean Waves•Drought•Fires

•Diseases•Plant diseases

Number of Disasters



•10 or more people reported killed •100 people reported affected•declaration of a state of emergency•call for international assistance

Bias: International database created in 1980s

IMPORTANT!!! This does not means that the number of eventsare increasing (the number of earthquake for example is constant)but the effects on human activity are increasing!!

Number of Disasters

Another bias:

Disasters are related. For example the casualty of december 2004 are listed as tsunami (should we count them as earthquake?).

The casualty of 1998 Papa New Guinea are listed as earthquake since majority of damages were related to the earthquake, but the majority of the victims were related to a tsunami generated by a landslide generated by the earthquake.

How much different hazards affects our society?

Total damages costs since 1900

Earthquake

Flood

Extreme Temp

Drought

Slide

Storm

Volcano

Wave

For all the natural hazard the global costs have been increasing

Total damages costs since 1900

Earthquake

Flood

Extreme Temp

Drought

Slide

Storm

Volcano

Wave

In term of costs Earthquakes, Tropical Storms, and Floods are the most expensive “geological” hazardsEpidemic and Famine have been historically the most devastating in term of casualtyPlague in middle age killed 1 every 3 european, Spanish Flu Pandemic 1920 30 million

Total damages vs Population

Increase in total damages correlate well with increase in population

Where do the Hazard Happens?

Geographical Distribution

Earthquake RiskVolcanoesStormsTornado

Almost all the areas of the planet are affected by some kind of hazardStable interior of continent more “safe” but often not suitable to life

Population distribution vs Risk map

Population distribution vs Risk mapThe human population is concentrated in “risky areas”

We need water, topography is controlling the hydrological cycleOften river flows in valleys controlled by fault positionRivers are more “manageable” in flat costal regions.Stable interiors of continents are often deserts.

We need soil: volcanoes produce excellent fertile soil. Water and plants are essential in soil formations (see point 1). River floodPlanes have excellent soil brought by periodic floods

We need communications way: flat costal areas are often the only suitable regions to build houses and roads.

We are too many and we start to build in places where we should notBuild and our ancestor were not building (river banks, beaches…)

Population distribution vs Risk map

Active tectonic is a necessity to have a planet where we can live!

We live in a dangerous planet but probably there is life On Earth because our planet is dangerous!

Documents

Natural Hazards