Homestake Meeting Minutes, 03/24/16
Attending: Daniel, Ross, Tanner, Gary, Gwynne, Victor, Levi, Vuk
Agenda:
1) Homestake array
- status of stations (WTP, Yates, 800)
Tanner: UMN antelope went down last Thursday, caught it within a week and copied the data from Homestake. Could not do this for HS, since the data is not available at Homestake. Can get it from baler eventually (one day of data). Gary has access to the HS computer, will try to copy the data directly.
Gary: observe low noise at low frequencies, digitizer may be limiting us. Noel at PASSCAL told us that we could boost the gain from 0 to 32, which will compromise the dynamic range but will lower the noise floor for the digitizer. May be able to do it remotely with Willard.
Vuk/Gary: Suggest to make a change for one of the stations and observe the impact over the next 2 weeks, and decide whether to stick with it or revert back in 2 weeks.
Tanner: will try to do this. Gary will help, contacting Noel.
- planning next visit: April 15-24
2) data analysis updates
UPDATED Results of Geochemical Data Analysis of Homestake:
PowerPoint
Levi: Updated the calculation, using input from Gary and Victor. The spread in estimated velocities is reduced now, after using the appropriate proxies. Get good agreement with streamer measurements at the 2000 level. This is an indication that the rock porosity at these depths is low. Gary will pass the standard formula to Levi to look at the porosity. Can also follow up with the Lab to see if they have any data on porosity. Would be useful to plot Levi's data, grouping the data by formation or by the rock type name. This could give a better sense of how the calculations compare to the measurements.
Results using the streamer data at 2000 level
powerpoint Ross: Presented the amplitude measured as a function of time and position along the 2000' drift. Do not see evidence of reflection off of the free surface or the open cut. Will try to estimate how large of the reflection signal we would expect. Also will try to repeat the analysis with a different f-t filter.
Victor: could get help from Boise State to do the analysis of the surface streamer data, to get the shallow surface wave speeds and P-wave speeds (from reflections). Gary: excellent, will try to get the timing to work in the coming few weeks. Victor: they may also try to detect tunnels wit reflection data.