From Harold E. Brooks
by e-mail
There are serious flaws in the logic behind using the seismic detection
method for tornado warnings (Technology, 5 April, p 26). The notion that a
“tornado works like a plunger trying to lift up or press down on the Earth’s
surface” is untested at this time and it is not clear that nontornadic severe
thunderstorms would not have the same effect. A large-scale test, particularly
of non-tornadic events, is necessary before the method can be used for public
safety.
Even if the creators are correct, their own description of their
method—which requires the tornado to touch down before the warning is
activated—means that the first touchdown will occur without warning. In
cases such as the tornado in Tulsa, Oklahoma, on 24 April 1993, where the
tornado touched down in the middle of the city, such a system would mean that
warnings would not be in effect when the tornado begins. In the Tulsa event, 6
of the 7 fatalities occurred within a minute or so of the initial touchdown.
The combination of radar, spotters, and improved communication have lowered
the annually averaged death toll from tornadoes in the US from nearly 200 as
recently as the 1970s to fewer than 40 this decade. It is not obvious that
seismic detection methods will provide substantial improvement beyond that.
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For more information on the origins and detection of tornadoes, see
http://www.nssl.noaa.gov/edu/tornado/.
