From: Roger Turk <73527.1356(--nospam--at)compuserve.com>
Date: Wed, 31 May 2000 15:56:59 -0400
On May 25, 2K, E.V. Leyendecker wrote:
I am puzzled by the last paragraph of your email. I am not aware of the
maps or references you are referring to when you talk about the USGS map
values being divided by 4 or of the criticisms from SEAOC about map values
being too low. To my knowledge, no such references exist. Would you
please provide the references you are describing for the benefit of me and
other users of this site?<<
On July 14, 1998, I received a packet of maps with the cover sheet stating:
"NEHRP MAPS 1994 EDITION."
Maps 6, 8, 10 and 12 show spectral accelerations for parts of California in
excess of 300%g. I recall seeing (an)other map(s) that had accelerations of
close to 4g.
The criticism of the maps by SEAOC was reported in Engineering News-Record.
IIRC, the report was on a BSSC meeting (Kansas City?) and the criticism was
that the maps then published by USGS did not show the actual accelerations
that would be experienced in an earthquake, but 1/4 the actual
accelerations. I have been unable to find my clipping of that article, but I
am sure that it will show up when I least expect it.
A. Roger Turk, P.E.(Structural)