Elasticity of U.S. Tornado Casualties

Talk given at the 9th European Conference on Severe Storms, Pula, CROATIA, Monday September 18th

Transcript

1. Elasticity of Tornado Casualties in the United States Human vulnerability is highest in urbanized areas of the Mid South James B. Elsner (@JBElsner) Department of Geography, Florida State University, USA September 18, 2017 Pula, CROATIA Help: Tyler Fricker
2. Take Home Points More urbanized areas of the Mid South are substantively and significantly more vulnerable to casualties from tornadoes than elsewhere in the United States. Greater vulnerability corresponds with a higher percentage of elderly people. Code/data used: https://rpubs.com/jelsner/TornadoCasualtyRisk SocArXiv: https://osf.io/preprints/socarxiv/ta6uh/
3. EF4 EF5 EF2 EF3 EF0 EF1 Number of Casualties 400 800 1200
4. 3590 1645 8 7 132 4 0 2 730 1516 413 4 857 393 500 980 747 226 194 1 163 274 1806 1302 12 939 46 221 5 3 51 0 147 307 2368 5 198 0 274 232 1529 1604 93 462 0 0 209 18 21 0 500 1000 1500 km N Injuries 0 to 1,000 1,000 to 2,000 2,000 to 3,000 3,000 to 4,000 347 114 0 0 3 0 0 0 82 94 19 0 37 25 40 71 38 6 5 0 6 12 219 98 2 46 3 9 1 1 2 0 5 20 132 0 6 0 10 7 149 100 1 12 0 0 6 0 2 0 500 1000 1500 km N Fatalities 0 to 50 50 to 100 100 to 150 150 to 200 200 to 250 250 to 300 300 to 350
5. 0 500 1000 1500 2000 2500 1995 1999 2003 2007 2011 2015 Year Number of People Exposed A 0 200 400 600 .01 .1 1 10 100 1000 10,000 Population Density [people/sq. km] Number of Tornadoes B 0 1 2 3 1995 1999 2003 2007 2011 2015 Year Energy Dissipation [PW] C 0 200 400 600 108 1010 1012 1014 Energy Dissipation [Watts] Number of Tornadoes D
6. 1 10 100 1000 .01 1 100 10,000 Population Density [people/sq. km] Number of Casualties A 1 10 100 1000 .001 .1 10 1,000 Energy Dissipation [GW] Number of Casualties B
7. Variable Value Number of Tornadoes 2192 Average number of casualties per tornado 12 Highest number of casualties 1564 Lowest number of casualties 1 Standard deviation of casualties 53 Average population density per tornado 223 Greatest population density 13949 Least population density 0 Standard deviation of population density 708 Average energy dissipation per tornado (W) 855,268,417,141 Maximum energy dissipation (W) 66,169,658,959,790 Minimum energy dissipation (W) 5,659,764 Standard deviation of energy dissipation (W) 2,896,044,608,799
8. Model log(ˆ µ) = ˆ β0 + ˆ β1 log(P) + ˆ β2 log(E) + ˆ β3 log(P) : log(E) Estimate Std. Error t value Pr(>|t|) ˆ β0 −3.0268 0.9606 −3.15 0.0016 ˆ β1 −1.8700 0.5281 −3.54 0.0004 ˆ β2 0.3825 0.0868 4.41 < 0.0001 ˆ β3 0.2200 0.0488 4.51 < 0.0001
9. −1.0 −0.5 0.0 0.5 1.0 1.5 .01 1 100 10,000 Population Density [people/sq. km] Energy Elasticity A −1.0 −0.5 0.0 0.5 1.0 1.5 .1 10 1000 100,000 Energy Dissipation [GW] Population Elasticity B
10. Population Density 100 [people/sq. km] Population Density 1000 [people/sq. km] Population Density 1 [people/sq. km] Population Density 10 [people/sq. km] .1 10 1000 .1 10 1000 0 5 10 15 20 0 50 100 150 200 0 2 4 6 8 10 0 20 40 60 Energy Dissipation [GW] Casualty Rate
11. 0 100 % 200 % 1 10 100 1000 Population Density [people/sq. km] Increase in Casualties Per Doubling of Energy A 0 100 % 200 % 1 10 100 1000 Population Density [people/sq. km] Increase in Casualties Per Doubling of Energy B
12. Rank State ˆ β3 p-value 1 Arkansas 1.023 0.000 2 Tennessee 0.717 0.001 3 Missouri 0.607 0.010 4 Kentucky 0.493 0.053 5 Illinois 0.417 0.021 6 Oklahoma 0.404 0.023 7 Alabama 0.347 0.056 8 Mississippi 0.329 0.106 9 Texas 0.308 0.001 10 North Carolina 0.286 0.458 11 Louisiana 0.246 0.126 12 Georgia 0.128 0.663
13. 100 [people/sq. km] 1000 [people/sq. km] 1 [people/sq. km] 10 [people/sq. km] 1 10 100 1000 1 10 100 1000 0 5 10 15 0 50 100 150 200 250 0 5 10 0 10 20 30 40 50 Energy Dissipation [GW] Casualty Rate Daytime Nighttime A Mid South 100 [people/sq. km] 1000 [people/sq. km] 1 [people/sq. km] 10 [people/sq. km] 1 10 100 1000 1 10 100 1000 0 2 4 6 8 10 12 0 20 40 60 80 0 2 4 6 0 5 10 15 20 25 30 Energy Dissipation [GW] Casualty Rate Daytime Nighttime B Everywhere
14. 100 [people/sq. km] 1000 [people/sq. km] 1 [people/sq. km] 10 [people/sq. km] 1 10 100 1000 1 10 100 1000 0 5 10 15 0 50 100 150 200 250 300 0 1 2 3 4 5 0 10 20 30 40 50 60 Energy Dissipation [GW] Casualty Rate Weekday Weekend A Greater Mid South 100 [people/sq. km] 1000 [people/sq. km] 1 [people/sq. km] 10 [people/sq. km] 1 10 100 1000 1 10 100 1000 0 5 10 15 0 20 40 60 0 2 4 6 8 10 0 5 10 15 20 25 30 Energy Dissipation [GW] Casualty Rate Weekday Weekend B Elsewhere
15. 2010 2016 State ˆ β3 Percent 65+ Percent 65+ 1 Arkansas 1.02 14.4 16.3 2 Tennessee 0.72 13.4 15.7 3 Missouri 0.61 14.0 16.1 4 Kentucky 0.49 13.3 15.6 5 Illinois 0.42 12.5 16.1 6 Oklahoma 0.40 13.5 15.0 7 Alabama 0.35 13.8 16.1 8 Mississippi 0.33 12.8 15.1 9 Texas 0.31 10.3 12.0 10 North Carolina 0.29 12.9 15.5 11 Louisiana 0.25 12.3 14.4 12 Georgia 0.13 10.7 13.1
16. 0 100 200 300 2011 2012 2013 2014 2015 2016 Year Casualty Rate Region Greater Mid South Elsewhere
17. Summary Tornado casualty counts from the SPC tornado record over the period 1995–2016 are fit to a statistical model. Storm strength and population are the independent variables and there is an interaction term. More urbanized areas of the Mid South are substantively and significantly more vulnerable to casualties from tornadoes than elsewhere in the country. Casualty rates are higher during the weekend for tornadoes occurring over the Mid South, but not elsewhere. Night and day casualty rates are similar regardless of where they occur. At the state level, increased vulnerability to casualties in more urbanized areas corresponds with a higher percentage of elderly people. What questions do you have?