Don:
ECFZ is eastern CA fault zone
The whole Los Angeles basin is included into the areas that I have seen affected

Well, I've seen the EHZ sensors acting up, now that you've corrected me with the VHZ sensors, I have to be more careful in the future about quoting off the top of my head (smile)

dfft is discrete fast fourier transform. I am using the fftw code that is available for linux, as it is optimized.