See The Destructive Force of Tornado Debris - WKRN, Nashville News, Nashville Weather and Sports

Storm chaser Jeff Piotrowski witnessed the destruction of the Joplin, MO tornado last year as he followed it into the city.

In a National Geographic special, he worked with engineers as they fired 2x4's our of a specially made air cannon at common housing exteriors such as brick walls and even concrete.

The special is called "Forecast Disaster" and airs October 4th & 5th.  It will include floods, tornadoes, earthquakes and avalanches.  Check your local listing for times.

Here is an excerpt.