Enhanced Fujita scale

Enhanced Fujita Scale (EF Scale) is a method used to classify the intensity of tornadoes based on the damage they cause. Developed as an improvement to the original Fujita Scale introduced in 1971 by Tetsuya Fujita, the Enhanced Fujita Scale was implemented in the United States in 2007. The scale aims to provide a more accurate assessment of tornado strength and potential damage, taking into account various types of structures and their vulnerabilities.

Overview

The EF Scale ranges from EF0 to EF5, with EF0 representing the weakest tornadoes, capable of causing light damage, and EF5 representing the most destructive tornadoes, capable of causing incredible damage. The assessment is based on post-storm surveys of the damage area, examining the types and degrees of damage to a wide range of structures and vegetation. This approach allows for a more nuanced understanding of a tornado's strength, as it accounts for differences in construction quality, natural variations in wind resistance, and other factors that can affect the extent of damage.

Scale and Damage Indicators

Each category on the EF Scale is defined by a set of Damage Indicators (DIs), which are types of structures or vegetation, and Degrees of Damage (DoD), which describe the extent of damage to the DIs. The scale considers 28 DIs, including single-family homes, schools, trees, and mobile homes, among others. For each DI, there are several DoDs, ranging from minor damage to complete destruction. The EF rating is determined by matching observed damage to the most appropriate DoD for the relevant DIs.

EF0

• Wind speeds: 65-85 mph (105-137 km/h)
• Damage: Light. May peel surface off some roofs; damage to gutters or siding; branches broken off trees; shallow-rooted trees pushed over.

EF1

• Wind speeds: 86-110 mph (138-177 km/h)
• Damage: Moderate. Roofs severely stripped; mobile homes overturned or badly damaged; loss of exterior doors; windows and other glass broken.

EF2

• Wind speeds: 111-135 mph (178-217 km/h)
• Damage: Considerable. Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely destroyed; large trees snapped or uprooted.

EF3

• Wind speeds: 136-165 mph (218-266 km/h)
• Damage: Severe. Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls; trains overturned; trees debarked.

EF4

• Wind speeds: 166-200 mph (267-322 km/h)
• Damage: Devastating. Well-constructed and whole frame houses completely leveled; cars thrown and small missiles generated.

EF5

• Wind speeds: >200 mph (>322 km/h)
• Damage: Incredible. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters; high-rise buildings have significant structural deformation.

Implementation and Use

The EF Scale is primarily used in the United States, but its methodology has influenced tornado intensity rating systems in other countries. The scale's adoption has led to more consistent and accurate tornado intensity ratings, facilitating better tornado research, improved building codes, and more effective disaster preparedness and response strategies.

Criticism and Limitations

While the EF Scale represents an improvement over the original Fujita Scale, it is not without its limitations. The scale's reliance on post-storm damage assessments can lead to underestimation of tornado intensity, especially in areas with few structures or in cases where tornadoes do not directly impact man-made structures. Additionally, the subjective nature of damage assessment can lead to inconsistencies in rating tornadoes.

See Also

• Tornado intensity and damage
• Tornado myths
• Tornado preparedness and safety
• Tornado outbreak