Each year hundreds of millions of dollars in property damage and approximately fifty to one hundred fatalities are produced by tornadoes, which represent the most violent of all forms of atmospheric storms. In recent years, by means of Doppler radar, con siderable success has been achieved in detecting tornadic storms. Such radar systems, however, cannot determine when a tornado is actually in contact with the ground. Based on eyewitness accounts combined with chance seismic recordings, there is strong evidence to indicate that a tornado in contact with the ground produces significant seismic signals, both long-period and short-period. The current program, which utilizes the Site Assessment of Tornado Threat (SATT) software, is designed to lead to a totally new way of detecting when a tornado is on the ground, based on this tornadic seismic signal (TSS). The resulting seismic detection of tornado (SDT) system has considerable potential for use by government agencies for the protection of the general populace, as well as for use by the individual citizen for personal safety within the home. A number of technical papers have been published dealing with our work in this area.
From the standpoint of both state and federal government agencies involved in the detection of tornadoes, an SDT network, when used in conjunction with Doppler radar, should provide an accurate, efficient method to determine when a tornado is actually on the ground. This would especially apply in the Southeast, where the low altitude of the cloud base, combined with the uneven terrain and numerous trees, tends to prevent timely visual sighting.
In addition to the development of SDT networks by government agencies, another SDT version could be developed for the individual homeowner. The alarm component of the system (referred to as an "Owl") would be installed in a residence in a manner similar to a smoke detector. The Owl would be activated by a signal from the Data Control Center (DCC) located at a central site such as a weather station, which would be linked to an SDT network of geophones (referred to as "Moles") buried in the surrounding region. The warning time provided would be on the order of two to four minutes, which should be sufficient for residents to move to the safest part of a home.
As part of a company-funded research effort dealing with the development of the Seismic Detection of Tornados (SDT), Engineering Analysis Inc. (EAI) has developed SDT instrument packages called "Snails" to be deployed during the Primary Tornado Season.