Measuring Natural Disasters – Tornados

In Business, News

In order to help explain certain natural disasters scientists have come up with systems to measure the severity of natural disasters like storms, earthquakes and tornadoes.  Most of these measures have been developed and revised over the last 100 years.  Several of these are described below.

Tornados

A tornado is a defined as a destructive vortex of rotating winds with the appearance of a funnel-shaped cloud moving beneath a large powerful storm system.

Funnel-shaped storm associated with a tornado
Funnel-shaped storm associated with a tornado

The EF Scale was adopted by the United States in 2007. The EF scale replaced the F (Fujita) Scale, which was developed by Dr. Theodore Fujita. The main purpose of the EF scale is to describe the amount of damage that was or could be done by a tornado. The real difference between the two scales is the estimated speed of the wind eminating from a tornado. The original Fujita scale was developed in the 1970s at the University of Chicago. The newer EF scale merely represents the ‘Enhanced’ Fujita scale.

Each of these scales are numbered from 0 to 5, one preceded by the letter F (fujita scale) and the other measured by the letter E, for example the weakest tornado would be an F0 or E0, depending on the scale used. The table below will help describe the wind speed ranges for each of these scales.

Fujita and Enhanced Fujita Scales

 

FujitaWind SpeedDamage PotentialEnhanced FujitaWind Speed
F040-72 mphlight damageEF065-85 mph
F173-112 mphmoderate damageEF186-110 mph
F2113-157 mphconsiderable damageEF2111-135 mph
F3158-207 mphsevere damageEF3136-165 mph
F4208-260 mphdevastating damageEF4166-200 mph
F5261-318 mphincredible damageEF5over 200 mph

 

While these measures were only recently developed in the 1970s, there’s no accurate measure of storms before this time, however as these scales were developed prior storms and their scales were estimated. Since 1950, there have been 59 officially rated F5/EF5 tornados in the United States as well as 1 in Canada. The most powerful storms ever, would obviously be EF or F5 storms.

Historic F5 storms:

 

YearLocationDeath Toll
1764Woldegk, Germany1 death
1845Montville, Seine-Maritime, France75 deaths
1899St. Croix County, Wisconsin117 deaths
1896Sherman, Texas73 deaths
1893Pomeroy, Iowa71 deaths

 

First Half of 20th Century (1900-1949)

 

YearLocationDeath Toll
1947Glazier/Higgins, Texas181 deaths
1936Tupelo, Mississippi216 deaths
1925Missouri/Illinois/Indiana695 deaths
1913Omaha, Nebraska113 deaths
1905Snyder, Oklahoma97 deaths

Please note, the storms in the 2 tables above are estimates based on the historic records and projections.

Second Half of 20th Century (1950-1999)

YearLocationDeath Toll
1953Waco, Texas114 deaths
1953Flint, Michigan116 deaths
1953Worchester, Massachusetts94 deaths
1955Udall, Kansas80 deaths
1984Ivanovo, Soviet Union92 deaths


21st Century Tornados

 

YearLocationDeath Toll
2011Joplin, Missouri158 deaths
2011Hackleburg, Alabama72 deaths
2011Tuscaloosa-Birmingham, Alabama64 deaths
2011Rainsville, Alabama25 deaths
2013Moore, Oklahoma24 deaths

 

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