Weather and Natural Disasters

Chicago area faces $20B tornado threat: Study

If a tornado like the one that ravaged Moore, Oklahoma in 2013 struck the Chicago area, potential damage could exceed $20 billion, reinsurer Swiss Re said on Monday.

The May 2013 Moore tornado, which topped the intensity scale for such storms, contributed to an outbreak that caused $1.1 billion in insured losses.

Read MoreNatural disasters don't dissuade home buyers

Swiss Re took the track of that tornado and laid it over Cook County, Illinois, which includes the Chicago area. Applying similar ratios of damage and loss to those experienced in Moore, the company arrived at the $20 billion property damage figure (which it acknowledged was not precise).

"Instead, this estimate of loss demonstrates the potential magnitude and far exceeds historical loss experience, even when the historical loss experience is adjusted for inflation, economic growth and population increases," the firm said in its report.

Read MoreExtreme weather may put disaster prep to the test

Dean Dye looks over a storm shelter in a home that was destroyed by a tornado on May 22, 2013 in Moore, Oklahoma.
Getty Images

"Densely populated and developed Cook County, Illinois has the greatest potential exposure to a violent and long track tornado" compared to areas like Dallas and St. Louis, Swiss Re added, with more than 112,000 people living in the damage zone of a Moore-like tornado.

"In short, an informed reexamination of history is instructive, for it dispels the myth that tornadoes cannot impact major cities," the firm concluded.