Picking up the twister's bad vibrations

摘要

Keeping your ear to the ground could give you early warning of an approaching tornado. Now an electronic ear that will do the job for you and should cost less than $50 is in prospect. In 1989, a tornado swept through the small town of Huntsville, Alabama, and killed 29 people. Afterwards, people told Frank Tatom, head of the local company Engineering Analysis, that they felt vibrations in the ground before the tornado reached them. Tatom calculated that a large tornado can transfer energy to the ground equivalent to half a tonne of TNT exploding every second- and that seismometers could detect the Shock waves.