PSN-L Email List Message

Subject: Re: tornados
From: "Thomas Dick" dickthomas01@.............
Date: Wed, 9 Nov 2005 21:16:16 -0600

 There are things that bother me about what I see. You have screen displays 
of the data. The difference between the Lehmans and the vertical I might 
excuse as differences in sensitivity -- sensitivity of the electronic pickup 
as well as the effect of the differences in the period for the Lehmans and 
the vertical. Since I used your suggestions on the Leymans, I could also 
excuse the differences between Lehmans and the vertical to be due to greater 
shielding. There is increased amplitude from the background "noise" on all 
three detectors that corelates to the same time on each detector and very 
close to the chronological time that areas were hit. When this storm came 
"ashore" after crossing the Ohio River for the last time in what I believe 
was in the 6:53 UTC minute it would have started up hill. At the time I 
"think" it hit Ellis Park - late in the 6:57 minute - it had to cross a 
raised highway (about 40 ft) to reach the horse park. About mid 7:07 minute 
it hits the trailer court and is slightly deflected from its NE path to a 
ENE by the elevated by-pass (highway). The spike early in the 7:11 minute 
might be the breaking of the highland in the immediate path of the tornado 
that runs N-S about 1/4 mile east of the trailer park.

You know I have trouble with power line spikes. There are none on the 
records of any of the detectors for this time frame -- well over an hour. As 
I mentioned earlier, record was "quiet" for the hour previous to the 
tornado. There is one other thing missing from the displays. That is 
lightning strikes. I frequently record close lightning strikes with these 
detectors. I know what they look like.  There were at least four very close 
strikes in my immediate area and eye-witnesses discribe the clouds being 
filled with lightning just ahead of the tornado. Why don't I see some?

Most of the "busy" activity on the seismograms seems to be late in the life 
of the tornado as it pulls east of me.Dr. Herrmann at St. Louis was 
wondering about frequencies above 5 hz -- things his seimographs would 
filter out. Maybe the vertical is susceptible to this frequency range. I was 
also considering the possibiliity (difference between early and late in the 
travel of this tornado) that might be caused by some form of phase shift 
like what a train whistle does as it passes. It was traveling unusually fast 
for a tornado.

This is why I used the words "strange" / "distinct" recordings, maybe the 
word unique might be more correct.  So, do I make sense?? 


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