Local mitigation strategy (LMS) - Volusia County Government

SECTION 5: HAZARD PROFILESTABLE 5.11: The Fujita Scale (Effective Prior to 2005)F-SCALENUMBERINTENSITYWIND SPEED(MPH)TYPE OF DAMAGE DONEF0 GALE 40–72F1 MODERATE 73–112F2 SIGNIFICANT 113–157F3 SEVERE 158–206F4 DEVASTATING 207–260F5 INCREDIBLE 261–318F6 INCONCEIVABLE 319–379Source: National Weather ServiceSome damage to chimneys; breaks branches off trees; pushesover shallow-rooted trees; damages to sign boards.Peels surface off roofs; mobile homes pushed off foundations oroverturned; moving autos pushed off the roads; attachedgarages may be destroyed.Considerable damage. Roofs torn off frame houses; mobilehomes demolished; boxcars pushed over; large trees snapped oruprooted; light object missiles generated.Roof and some walls torn off well-constructed houses; trainsoverturned; most trees in forest uprooted.Well-constructed houses leveled; structures with weakfoundations blown off some distance; cars thrown and largemissiles generated.Strong frame houses lifted off foundations and carriedconsiderable distances to disintegrate; automobile sized missilesfly through the air in excess of 100 meters; trees debarked; steelre-enforced concrete structures badly damaged.These winds are very unlikely. The small area of damage theymight produce would probably not be recognizable along withthe mess produced by F4 and F5 wind that would surround theF6 winds. Missiles, such as cars and refrigerators would doserious secondary damage that could not be directly identifiedas F6 damage. If this level is ever achieved, evidence for it mightonly be found in some manner of ground swirl pattern, for itmay never be identifiable through engineering studies.According to the NOAA Storm Prediction Center (SPC), the highest concentration of tornadoes in theUnited States has been in Oklahoma, Texas, Kansas and Florida. Although the Great Plains region of theCentral United States does favor the development of the largest and most dangerous tornadoes (earningthe designation of “tornado alley”), Florida experiences the greatest number of tornadoes per squaremile of all U.S. states (SPC, 2002). Figure 5.6 shows tornado activity in the United States based on thenumber of recorded tornadoes per 1,000 square miles.Volusia County Multi-jurisdictional Local Mitigation StrategyFebruary 20105:33