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Homestake Meeting Minutes, 03/10/16
Attending: Tanner, Gary, Ross, Daniel, Vuk, Pat
Homestake array
status of stations (WTP, Yates, 800): Still problems with Yates, and one of the masses at 800 seems stuck, have to recenter it. WTP seems to be working fine, although the voltage maxes out to 12-13V, less than other stations. There were data gaps from 4850C, probably due to blasting. Probably lost power too, in two 10hr periods, so 20hrs total. Data flow going ok.
Gary: looked at the data, looks like they used a sequence of charges, it would be good to try to deconvolve them. Would need to know the timing of the explosions.
data analysis updates
Tanner: took an event from Gary's catalog, tried to identify the Rayleigh part of it, about 30sec from a local blast. Filtered the data, estimating the frequency of the wave by eye. Then do principal component analysis: compute the covariance matrix, then its eigenvalues, then project the motion onto the two main eigenvectors. Real data looks messy, tried with simulations and it worked fine. Probably have to improve on the narrowband filter. Will have some plots for the next meeting. Daniel provided information too, will try to go through it an include it in the coming days.
Daniel: all sounds great. A more common approach people use is to fix the source direction, and then force the azimuth.
Daniel: showed plots that can be used to convince ourselves that we are looking at the Rayleigh wave, by plotting the velocity vs frequency or period. Velocity increases at lower frequencies (larger wavelength) for Rayleigh waves and this is what you would look for.