US Vulnerability to Natural Hazards

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increase awareness of natural disasters and the predictable consequences of high-risk ... largely due to increases in population and wealth density in disaster-.
US Vulnerability to Natural Hazards

NATURAL DISASTERS result from the coincidence of natural

events with the built environment. To reduce natural disasters, we need to increase awareness of natural disasters and the predictable consequences of high-risk land-use. By superimposing population density with predicted ground motion from earthquakes, historical hurricane tracks, historical tornado locations, and areas within the flood plain, we are able to identify locations of high vulnerability within the United States. Although their frequency varies considerably, the annualized losses for disaster relief from hurricanes, earthquakes, and floods are approximately equivalent and represent over 75% of federal emergency assistance. Tornadoes cause less damage, but are responsible for a significant percentage of deaths.

2.5

Federal Disaster Relief as a Percentage of GDP 0.07 0.06

2.5

1.9

0.04

3.2

0.03

1.5

0.02 0.01

2.1

0.00

3.0

1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 Fiscal Year

6.8

-2

-1

-1

0

11.0

1

7.1

9.7 1.7

-3 -4

3.3

3.7

Earthquake Frequency w/ Selected Events

12.2

9

Magnitude

7

3

10

100

1,000

10,000

100,000

5.3 16.9

0.9

4

minor earthquake felt by humans

1

0.1

5

light earthquake some property damage

0.1

26.6

6

moderate earthquake property damage

4

6.1

7

strong earthquake damage ($ billions) loss of life

Long Island, NY (1884)

5

9.5

8

major earthquake severe economic impact large loss of life

6

16.6

9

great earthquake near total destruction massive loss of life

New Madrid, MO (1812) San Francisco, CA (1906) Charleston, SC (1886) Loma Prieta, CA (1989) Northridge (1994)

8

15.9

10

Alaska (1964)

6.9

10.7

4.5

1.3 For the purposes of this analysis, population is used not only to represent human exposure to risk, but also vulnerable societal infrastructure. In the figure above, the correlation coefficient of income and population by county is .9919. With the exception of about two dozen counties, where the estimated value is too high, and a few large counties where the estimated value is too low, population density can be used as a proxy for societal infrastructure.

10

4.9

4.4

-2

Log (County Population in Millions)

12.7

4.5

6.0

1.5

0 -3

5.7

2.1

0.8

1 -4

3.1

3.6

2 Log (County Income in Billions)

7.0

1.7

Aggregate Income versus Population by County

1.1

6.5

2.5

1.0

4.3

The costs of natural disasters have been increasing exponentially, largely due to increases in population and wealth density in disasterprone areas. The figure above shows the federal government’s expenditures for natural disasters as a percentage of Gross Domestic Product (GDP). Even when accounting for the exponential rise in GDP over the last four decades, the costs of natural disasters have tripled.

5.2

2.3

0.6

1e+06

3

Number of Events per Century

Hurricanes (1899-2000)

In general, the number of seismic events in a region increases by a factor of 10 for each unit of decrease in magnitude. This empirical observation, known as the Guttenberg-Richter relation, applies to earthquakes in the United States. As the figure above shows, we should expect approximately 2 magnitude 8, and 20 magnitude 7 earthquakes each century.

S3

S4

S5

Tornadoes (1950-2000)

30

Population (2000 Census)

100,000

Hurricane Landfalls/ Century 11 – 30

Percent of Area in Floodplain by State

31 – 72

Earthquake Acceleration 8 – 10

11 – 20

21 – 40 41 – 100

Peak Ground Acceleration (%g) with 10% Probability of Exceedance in 50 Years

Values on Map Correspond to the Percentage of Each State Within the Floodplain

FEMA Cost per Person in Floodplain per Year

Hurricane Tracks at Approximately 30 Year Intervals

Tornado Frequency (TX, OK, KS)

450

Number of Torndadoes 50-95

%

0.6

FEMA relief + 15% SBA loan activity

0.05

400

1899 - 1927 1928 - 1960

Tornado Strength

1928 - 1960 1961 - 1990

1961 - 1990 1991 - 2000

F0 F1 F2 F3 F4 F5

350

300

250

Total Tornadoes

Gregory van der Vink, Sarah Apgar, Andrew Batchelor, Caroline Carter, David Gail, Andrew Jarrett, Naomi Levine, W. Jason Morgan, Michal Orlikowski, Thomas Pray, Meryl Raymar, Asher Siebert, Tsering Wangyal Shawa, Clinton Wallace

200

El Niño / La Niña 150

El Niño Year

(Dot proportional to event size)

This poster was prepared for the Congressional Natural Hazards Caucus as part of the undergraduate course Geo499: Investigating Natural Disasters, taught by Gregory van der Vink at Princeton University. Support for the course was provided by the Department of Geosciences and Princeton University’s Science and Technology Council. Poster development and design by Jason Mallett, IRIS Consortium. Special thanks to David Applegate, Peter Folger, and Christel Hennet.

100

La Niña

Percent

50

0 1950

1953

1956

1959

1962

1965

1968

1971

1974

1977

1980

1983

1986

1989

1992

1995

There are about 1,500 tornadoes in the US each year. The increase, particularly in F0 tornadoes, is probably due to improved detection capabilities. The correlation with El Niño years is not well-defined.

0-5 5 - 10 10 - 20 20 - 30

Dollars 0 - 100 100 - 1000 4500 - 8000

The area of the United States within the 100-year floodplain is approximately that of Texas. At present, more than 3 million households are in floodplains, and each year, the number increases. States that have the greatest percentage of area in the floodplain however, do not necessarily incur the largest number of flood disasters on a per capita basis – perhaps reflecting better land-use policies for those states. According to FEMA, only 2% of the flood insurance policy base is responsible for nearly 40% of the payments made by the National Flood Insurance Fund.

In the last century about 170 hurricanes have struck the United States. Each year in the Atlantic, approximately six hurricanes form, with one or two making landfall. The frequency, strength, and location are affected by wind shear and sea-surface temperatures, both of which are part of the greater El Niño and multi-decadal cycles and patterns. Historical tracks show East-West oscillations in 30-year periods. If this 30-year oscillation continues, hurricanes will become more frequent along the northern part of the Eastern Coast.

Each year, Congress appropriates billions of dollars in emergency assistance to states hit hard by earthquakes, floods, hurricanes, tornadoes and other natural disasters. The Senate Hazards Caucus provides ways the local, state and federal government to better prepare for and help mitigate the costs of natural disasters.