Sunday, August 2, 2009

The Tri State Tornado of 1925

Tornados, or “twisters”, are violently rotating funnels of air that are spawned by severe thunderstorm activity, and are capable of producing extreme winds in excess of 300 mph (485 kph). This level of severity will produce catastrophic damage to even the strongest buildings and is capable of flinging houses off their foundations, and hurling automobiles and people through the air for considerable distances.

Flying debris produced by tornados is often lethal to anyone caught outside, and many people have also been killed by structural collapse when trying to seek shelter inside a building or trailer.

“Tornado alley” in the United States is the world’s twister hotspot, and covers parts of Texas, Oklahoma, Kansas, Nebraska, Illinois, Missouri and Indiana. This is the rolling open country of the Great Plains where cold air streaming southwards from Canada can collide with warm, humid air moving up from the Gulf of Mexico to generate lines of massive, severe thunderstorms, together with their violent tornadic offspring. This set of circumstances can occur almost anytime, but is most common during the months of spring and summer.

Perhaps the most infamous and extreme event of this type in modern recorded history occurred on March 18 1925, when a severe thunderstorm developed across southeast Missouri and generated a particularly violent twister. This turned out to be unlike any other tornado encountered before or since, and it cut a swathe of unparalleled death and destruction across three states before finally dissipating over 200 miles (322 km) from its place of origin. This was the deadly Tri State Tornado or TST.

The “normal” twister will only last a fairly short period, typically around half an hour or so. But TST was different – it lasted about three and half hours, producing an extended period of almost continuous destruction as it ripped its way across the countryside, travelling at speeds of up to 60 mph (97 kph). The actual wind speed inside the funnel was estimated to have been towards the top end of the tornado scale, with later analysis of the damage trail indicating possible winds around 300 mph (485 kph).

TST ripped through some twenty sizeable townships, including Gorham, Murphysboro, DeSoto, West Frankfort and Parrish, all in southern Illinois, killing a total of 488 people, and causing utter destruction right across the area. Parrish, in particular, was so completely ruined that it was never rebuilt, and contemporary photographs taken in some of the other areas show settlements that closely resemble some of the French and Belgian villages destroyed by shellfire in World War One.

The town of Griffin Indiana - all but flattened by the Tri State Tornado. Image: Wikipedia Commons (Click on image to enlarge)

Perhaps most tragically, because it was a Wednesday, school was in and several schoolhouses were directly hit, with 17 students dying in Murphysboro and another 33 at DeSoto.

Eventually the tornado crossed the border into Indiana, where it inflicted massive damage to the townships of Griffin and Princeton, before finally abating after the longest continuous rampage of any known twister.

In all, 695 people died - still the record by far for an American tornado, over 2000 were injured and some 15,000 homes demolished.

Subsequent investigation of the twister’s path revealed a monstrous gouge of destruction across the countryside, some 219 miles (353 km) long and about three quarters of a mile (1.2 km) wide.

Illustrated report of the disaster in the Herald Examiner describing the destruction of Murphysboro.
The number of casualties in the report was happily an overestimate.
Image: Wikipedia Commons

The Tri State Tornado remains the benchmark of severity against which all US tornados are measured, and is a perpetual reminder of how deadly twisters can become under the right conditions.

For a comparison of this event with the recent Oklahoma disaster see

Reference: “Disasters, Events and Moments that Changed the World”, Richard Whitaker, New Holland Publishing, 2007

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