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RE: Artificial Time Histories Generation

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Dear Walter,

Digital data is kept at the LAmont Doherty Earth observatory at Columbia
University.  It is an excellent data base.

The data for the lamb project and the Memphis generated traces are worth
looking at.

The concept of taking a fourier inversion and playing with real component to
generate a revised time domain is an interesting idea. I might suggest that
you need to take care around the natural period of the structure and the
associated ground if you are doing modelling.  The Nahanni earthquake had a
savage peak in the spectra at low freq.  That is one of the problems, if you
are designing a structure near this peak you dinna want to smooth it out to
much and playing with the FFT might do that.  

Jacob from Lamont said it best with the advice that there just isn't the
data available.  If I was doing the design just as a check I would determine
the natural frequancy then run the three componets for one of the big quakes
with a peak near that natural freq and consider the results.  You might not
use them but it would make one feel better.

good hunting

john nichols

At 19:48 20/05/98 -0500, you wrote:
>Dr. Rangelow :
>Thank you very much for the information, I'm going to contact Dr. Naumoski
>to get his software. I would really appreciate any details of your
>experience with this software. 
>Here in Peru, our new seismic code requests a Time History analisys for
>special structures with at least five seismic registers of real earthquakes
>or artificially generated. Due we don't have the information for real
>earthquakes, we would like to create artificial registers. 
>If you know about digital eartquake registers available of any place I
>would really appreciate it.
>Thanks a lot for your help.
>Walter Sheen, CE
>Lima, Peru