Fujita vs Enhanced Fujita Scale

By: Amy Schmidt
By: Amy Schmidt

The Fujita scale was first introduced in 1971 by Dr. T Theodore Fujita. He wanted something that categorized each tornado by intensity and area. He devised a scale that was divided into six categories, F- zero through F- five. Dr. Fujita wanted to estimate wind speeds associated with the damage caused by a tornado. The first application of this scale was the Super Outbreak of 1974, when 148 tornadoes touched down in thirteen states. After that, the Fujita scale became the definitive scale for every tornado in the United States.

Over the years, the Fujita scale revealed some weaknesses. The estimation of wind speed in relation to damage was difficult to apply with no damage indicators. Often the Fujita scale was based on the worst of the damage in an area, even if it was just one building or one house. Another weakness of the Fujita scale, was that it overestimated wind speeds greater than F-three.

The Enhanced Fujita scale was introduced in 2007. The main point of the enhanced scale, was that it would continue to maintain the original database. There was to be conformity between the original Fujita scale and the Enhanced Fujita scale. A few additions were to be made as well. The Enhanced Fujita scale would have a more consistent assessment of damage. This would include photos and examples, and not only structures, but vegetation as well.

When using the Enhanced Fujita scale to determine a tornado’s EF- rating, there are twenty eight damage indicators. Each indicator has a description of the typical construction for that category of indicator, as well as materials that make up the type of building. After the Damage Indicator is selected, the degree of damage needs to be applied.
Each Degree of Damage is asssessed and an expected wind speed given, depicted by a lower bound and upper bound. An example would be Degree of damage 8 to an automobile showroom. The expected wind speed for complete destruction would be around 157mph, however wind speeds between 138 and 181mph could also completely destroy the building.

Wind Speeds in the Original Fujita Scale:
F0: 45-78 mph
F1: 79-117 mph
F2: 118-161 mph
F3: 162-209 mph
F4: 210-261 mph
F5: 262-317 mph

Wind Speeds in the Enhanced Fujita Scale:
EF0: 65-85 mph
EF1: 86-110 mph
EF2: 111-135 mph
EF3: 136-165 mph
EF4: 166-200 mph
EF5: Over 200 mph

The 28 Damage Indicators used in applying the Enhanced Fujita Scale:
1: Small barns, farm outbuildings
2: One- or two- family residences
3: Single-wide mobile home
4: Double-wide mobile home
5: Apartment, condo, townhouse (3 stories or less)
6: Motel
7: Masonry apartment or motel
8: Small retail building (fast food)
9: Small professional building (branch bank)
10: Strip mall
11: Large shopping mall
12: Large, isolated retail building
13: Automobile showroom
14: Automotive service building
15: School- 1 story elementary (interior or exterior halls)
16: School- jr. or sr. high school
17: Low-rise (1-4 story) building
18: Mid-rise (5-20 story) building
19: High-rise (over 20 stories) building
20: Institutional building (hospital, university)
21: Metal building system
22: Service station canopy
23: Warehouse
24: Transmission line tower
25: Free-standing tower
26: Free standing pole (light, flag)
27: Tree- hardwood
28: Tree- softwood

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