Natural Hazards and
Risks: so far what do
you know?
Natural Hazard versus
Population

Where there
is an
interaction
between
hazard and
population,
there is the
potential for a
disaster or
higher risk.

What factors increase the
risk?
Some factors that increase
risk are:



Population density
Location in respect to the hazard
Economic standing
Global population is expected to
reach 7 billion by 2045
•
•
•
The Last 10,000 Years of Human
History
Flat population growth curve until 8,000 years ago
– Agriculture established
– Domestication of animals
– Growth rate increased to 0.036%/year
By 2,000 years ago, population ~200 million people
– Better shelter, food, water supplies  faster population growth
– Growth rate of 0.056%/year
By 1750, population
~800 million people
Figure 1.8
The Last 10,000 Years of Human
History
• By 1750, population ~800 million people
– Public health principles, causes of disease recognized
– Birth rates soared, death rates dropped
•
•
•
•
•
•
1810:
1925:
1960:
1974:
1987:
1999:
~1
~2
~3
~4
~5
~6
billion
billion
billion
billion
billion
billion
Insert figure 1.10 here
• By 2013, projected population ~7 billion
• Population growth is exponential
Figure 1.10
The Human Population
Today
• Present population: Almost 7 billion
– Growth rate = 1.2%/year
– Doubling time = 58 years
• Growth rate =
fertility (birth) rate – mortality (death)
rate
• Human population grows by about 80
million people per year
Future World
Population
• Demographic transition theory:
– Mortality and fertility rates decline from high to low levels because of
economic and social development
• Population Reference Bureau estimates world
population growth rates are dropping
– From 1.8% in 1990 to 1.2% in 2008
– Due to urbanization and increased opportunities for women
Urban Growth: change from
rural to urban population
More developed regions
•The world’s
urban population
is now growing
by 80 million
persons per year
World trend
UNPF
Least developed regions
Megacities: greater than 10
million
Tectonic Map of the World
Megacities
By 2030, 66% of
the world’s
population will
live in urban
areas.
Sao Palo, Brazil, 18
million people
How does this
type of
environment
increase the
amount of risk?
Global Economies
Future World
Population
Figure 1.12
Population Distribution- not
uniform worldwide
Demographic Divide
Demographic Divide
Demographic trends
Developed countries
 More education a
woman receives the
less children she will
have
 Higher life expectancy
Developing countries
 Higher birthrates
 Larger % of pop., young
 Lower life expectancy
 Become refugees due to
political unrest
 1 in 7 people in the world
live in slum conditions
Armenia, 1988
Developing
Countries

Pakistan, 2005
Poorly designed or
weak traditional
structures
Iran, 2001
People often inhabit floodplain,
hillsides and other “leftover”
areas.


Lack resources
shelters are
poorly
constructed and
population is
concentrated.
Problem?
Densely populated regions





Lack of strong structures
Narrow streets: inhibits exit of
people and entrance of emergency
vehicles
Lack of infrastructure: water
Closely packed wood structures: fires
spread quickly
Lack of emergency services
Haiti: magnitude 7 earthquake
January 12, 2010
222,570 people killed,
300,000 injured, 1.3
million displaced,
97,294 homeless
Enriquillo-Plantain Garden fault system
Haiti

2 million people in
Port au Prince
• Infrastructure for
100,000


Housing: lack of
reinforcement
75% of population
live on less than
$2/day
Chile, M8.8 earthquake
Subduction zone
528 people killed,
many injured and at
least 500,000 houses
damaged
Chile
Building codes similar
to the United States
 Largest earthquake
ever recorded in 1960
 Magnitude 9.5
 Magnitude 7.1,
January 3, 2011
 Recovery continues
About 30% of the
population lives in
poverty
ECONOMIC STANDING: VERY
IMPORTANT FACTOR
REGARDING RISK AND
RECOVERY
Deaths due to natural disasters

Most mega-killer
disasters occur in
densely populated
belt through Asia,
along Indian Ocean
– number of
fatalities is
proportional to
density of
population
Loss of Life versus Population:
1947-1980
# of events
N. America
Carr./C.A.
S. America
Europe
Asia
Africa
Oceania
180-eq
77
30,613
38,837
7,750
354,521
18,232
18
7-tsunami
60
4,459
18-volcanic
96
151
440
2,000
2,805
4,000
Since 1980- major events
# of events
N. America
Mex./Carr.
S. America
Europe
Asia
Africa
Middle East
Earthquakes
~120
288,000
38,837
? 26-Italy
43,126
?
59,900
Tsunami
~180,00
Volcanic
?
?
23,000
?
?
Natural Disasters: 1950-2005


The number of
disasters through
time has increased
Why?
• More hazards?
• More people in the
way of hazards?
Disaster Frequency and
Magnitude

Common

Rare
Low
High
Magnitude

The greater the
magnitude, the rarer
the event
How many people
understood the
potential hazard from
a tsunami before
2004?
Haiti earthquake?
Disaster Magnitude and Return
Period

Long

Brief
Low
High
Magnitude
The greater the
magnitude, the
longer the return
period
When was the last
time a large
earthquake occurred
in California?
Economic Loss

Includes destruction of:





Buildings and roads
Water and electricity
Businesses and industries
Employment
Takes years to determine
Increase in economic loss with time
Insured losses

Developed
countries have:
• higher insured
losses
• Lower number of
fatalities
•

Developing
countries have:
• lower insured losses
• Higher number of
fatalities
Increase in economic losses over time is result of increase in human
population and urbanization
Carrying Capacity
• How many people can Earth support?
– Calculations of carrying capacity vary
considerably
– Increasing amounts of food can be produced
– People can migrate from areas of famine or
poverty to less crowded or wealthier areas
– BUT Earth’s
resources are
finite, so
solutions are
temporary
Figure 1.15
Carrying Capacity
• Example of Rapa Nui (Easter Island)
– Isolated Pacific island with poor soil and little
water
– Settled by 25-50 Polynesians in 5th century
• Survived easily on chickens and yams,
plenty of free time
• Developed elaborate competition between
clans with moai (statues)
– Civilization peaked at 1550,
with population of ~7000
Figure 1.14
Carrying Capacity
• Example of Rapa Nui (Easter Island)
– Reached by a Dutch ship in 1722
• Found about 2,000 people living in caves
• Primitive society, constant warfare
– Rapa Nui’s carrying capacity had been
drastically lowered by society’s actions:
• Transportation of moai had required cutting down trees
• Erosion of soil made yams scarce
• Lack of canoes made fishing difficult and escape impossible
Bottom Line?



Larger events are less common
Increase cost due to increase economic
loss
Increase of population
• Change from rural to urban
• Structures and population concentration
without consideration of hazards
• Carrying capacity: the ability for the
population to live and thrive