Tornadoes have been known to strip asphalt pavement, and even scrape the ground with their winds, but we don't know if they can actually dig into the ground.

The deadliest US tornado was in 1925 on March 18. It is called the "Tri-state" tornado and killed 695 people along its 219 mile track through Missouri, Illinois and Indiana.

Not that we know of yet...but the thunderstorms that produce tornadoes release energy that builds up in the atmosphere.

On the average tornadoes kill about 60 people each year, mostly from flying or falling debris.

The very center of the tornado is probably almost calm, but may have some downward motion in it. There have not been any direct measurements of the winds because the instruments used to measure wind speed can't survive long enough to measure the eye.

The most common and practical way to determine the strength of a tornado is to look at the damage it caused. From the damage, we can estimate wind speeds. Professor Theodore Fujita developed a scale to help us evaluate damage and classify tornadoes. In summary, the Fujita Scale ranges from F0-F5. F0 tornadoes have winds of 40-72 mph and can break branches off of trees and damage signs. F5 tornadoes have winds from 261-318 mph, which can lift houses off foundations, and make automobiles as dangerous as a missile flying through the air.

An "Enhanced Fujita Scale" will be implemented by the National Weather Service by February, 2007. In a nutshell, the enhanced F scale was developed to rate tornadoes in a more consistent and accurate manner. It will still rate tornado categories from F0 to F5, but the ranges of wind speed in each category are now more accurate. It takes into account more variables than the original scale did when assigning a wind speed rating to a tornado, incorporating 28 damage indicators such as building type, structures, and trees. For each damage indicator, there are 8 degrees of damage ranging from the beginning of visible damage to complete destruction of the damage indicator. The original F scale did not take these details into account. Go to: www.spc.noaa.gov/faq/tornado/ef-scale.html

The most common and practical way to determine the strength of a tornado is to look at the damage it caused. From the damage, we can estimate the wind speeds. An “Enhanced Fujita Scale” was implemented by the National Weather Service in 2007 to rate tornadoes in a more consistent and accurate manner. The EF-Scale takes into account more variables than the original Fujita Scale (F-Scale) when assigning a wind speed rating to a tornado, incorporating 28 damage indicators such as building type, structures and trees.

The damage from tornadoes comes from the strong winds they contain. It is generally believed that tornadic wind speeds can be as high as 300 mph in the most violent tornadoes. Wind speeds that high can cause automobiles to become airborne, rip ordinary homes to shreds, and turn broken glass and other debris into lethal missiles. The biggest threat to living creatures (including humans) from tornadoes is from flying debris and from being tossed about in the wind. It used to be believed that the low pressure in a tornado contributed to the damage by making buildings "explode" but this is no longer believed to be true.

While it may appear tornadoes target mobile home parks, they actually do not. An F1 tornado might do significant damage to a mobile home, and cause minor damage to a site built home -- looking like the tornado "skipped" the house. Mobile homes are, in general, much easier for a tornado to damage and destroy than well-built houses and office buildings. A mobile home, or manufactured home, by definition, is built at a factory and taken to the place they will occupy--so they are much more affordable than a house built on-site. Also, they are often built with lighter-weight materials, which do not hold up well in tornadic winds.

Straight-line winds can also destroy a mobile home as easily as a tornado, especially one that is not anchored. Any wind gust that is sustained for 3 seconds over 50mph can cause damage to mobile homes.

Some states are beginning to require storm shelters for their residents. The statistics definitely support this – 7% of our population lives in mobile homes, and almost half of tornado fatalities in the U.S. occur in mobile homes. The problem of warning and sheltering mobile home residents has become the biggest obstacle to continuing to reduce death tolls from tornadoes.