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Project 2: Summarizing and Displaying Property Damage from Tornadoes
Jim Kompanek
Introduction:
On May 3, 1999, the residents of Oklahoma suffered the largest outbreak of damaging tornadoes (Figure 1) in their state's history, with over 40 people killed and 675 injured as a result (NOAA 1999a). The following figures displays approximate damage statistics, as well as a brief analysis of the damage. All data was obtained from King 2006. For the purpose of this project, the following thematic maps were created with ESRI ArcMap 9.1:
Further analysis (Try This!) will include:
Figure 1. Tornadoes as observed from a NOAA weather satellite on May 3, 1999. Image courtesy of NOAA. Used here for educational purposes only (NOAA 2006b).
Tornado Paths:
Figure 2. Tornado paths according to F scale, with darkness indicating magnitude, in Oklahoma. Figure created using ESRI ArcMap 9.1. Please click on image for full size graphic.
As can be observed in Figure 1, numerous tornadoes touched down, leaving a path of destruction throughout central Oklahoma, as well as adjoining states. Figure 2 indicates the path of these tornadoes, according to their respective F scale, with the darkness of color indicating the respective strength of each tornado. Numerous counties were clearly impacted by each tornado. The respective damage of each tornado, as can be seen the following figures, will show that the cost in property and dollars, will not entirely be linked to the strength of the tornado, but a combination of factors including the number structures, as well as population.
Housing Unit Density:
Figure 3. Tornado paths according to F scale and impacted counties according housing density. Figure created using ESRI ArcMap 9.1. Please click on image for full size graphic.
According to Figure 3, Oklahoma County, followed by Cleveland, has the highest population density of all the impacted counties. Even though these counties don't appear to bear the brunt of tornado activity, it is likely they would suffer higher property damage than surrounding counties, due to their higher population density.
Property Damaged:
Figure 4. Tornado paths according to F scale and total number of damaged residential housing units, including houses, mobile homes, and apartments. Figure created using ESRI ArcMap 9.1. Please click on image for full size graphic.
As predicted above, Oklahoma, followed by Cleveland Counties had the highest amount of property damage, even though other counties appeared to have the higher levels of tornado activity. For a tornado to cause damage to residential housing units, a county must have housing units to begin with. Even a week tornado will do more damage to an urban area, than a very strong one will do a pasture.
Property Destroyed (in raw numbers):
Figure 5. Tornado paths according to F scale and total of destroyed residential housing units, including houses, mobile homes, and apartments. Figure created using ESRI ArcMap 9.1. Please click on image for full size graphic.
Figure 5 indicates the total number of destroyed housing units in each of the impacted counties. As with the previous figure (see Figure 4), Oklahoma, followed by Cleveland Counties suffered the loss of the most housing.
Property Destroyed (in dollars):
Figure 6. Tornado paths according to F scale and total dollar amount of destroyed residential housing units, including houses, mobile homes, and apartments. Figure created using ESRI ArcMap 9.1. Please click on image for full size graphic.
As previously discussed, the destructiveness of each tornado was linked to the overall population density of the impact area. As seen in the previous figures (see Figures 4 and 5), Oklahoma and Cleveland Counties received the highest level of both property damage and complete destruction of housing units. Not surprisingly, this inevitably lead to the highest level of monetary damage to the same counties. As a result of the May 1999 tornadoes in Oklahoma, the dollar amount of destroyed or damaged residential housing was highest in both Oklahoma and Cleveland Counties (Figure 6).
Housing Unit Density (according to census tract):
Figure 7. Tornado paths according to F scale and housing density by census track. Figure created using ESRI ArcMap 9.1. Please click on image for full size graphic.
As can be seen in Figure 7, there were four primary population centers, in Oklahoma, Cleveland, Garfield, and Payne Counties, that were impacted by the tornadoes. Figure 3 may have implied that housing density was evenly distributed throughout each county. As observed in Figure 7, there were four primary clusters of high density areas. Luckily, for the residents of Oklahoma, each of the tornadoes narrowly missed these areas, with the exception of Oklahoma County, where an F5 tornado went through the southeastern limits of a large urban area. If any of these tornadoes landed even a few miles from their actual path, the results could have been even more catastrophic.
References Cited:
King, Beth
