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Homestake Meeting Minutes, 12/08/17

Attending: Andrew, Jan, Pat, Ross, Vuk, Daniel, Michael, Gary


  • Next Meeting: Jan 12?
  • Data analysis topics
    • Data corrections, frame production (Gary/Daniel/Pat)
    • Event catalog (Gary/Ross)
    • Radiometer updates (Pat, Andrew)
    • Parameter estimation for Rayleigh and Love (Pat)
    • Teleseismic events and Wiener filtering (Daniel, Michael)
    • Very-long-periods (Ross)
    • Velocity from noise correlations (Daniel)
      • Model selection?
    • Pull together all velocity measurements to start making comparisons (all)
  • Papers
    • Homestake Array Summary paper:
      • Leads: Vuk, Gary, Victor
      • Submitted to Seism. Research Lett.
  • Active excitation overview paper
    • Leads: Gary, Ross
    • Others: Victor, Daniel,…
    • Draft of the paper exists, as a report for IRIS. Gary will be adopting it to a publication. Don't have a particular date in mind.
    • Vuk: Gary reports via email that he expects to be working on this paper over the holiday break.
  • Surface Active Excitation
    • Leads: Victor, Boise
    • Others: Gary, Ross
    • Plan to invite the Boise group to give us a presentation in Sep or Oct 2017, when they are ready with their paper.
  • Underground Active Excitation:
    • Lead: Gary, Ross
  • Parameter estimation for the Rayleigh and Love eigenfunctions (amplitude vs depth dependence).
    • Leads: Pat, Daniel
    • Also contributing: Victor, Vuk, Levi
  • Estimating directional and modal composition of the seismic noise. (Pat, Levi, Vuk)
    • Leads: Pat, Vuk, Levi
  • Wiener filter application
    • Leads: Jan, Michael
    • Latest version: wiener.pdf. Needs minor modifications of figure 6, and still need to rewrite conclusions.
    • Vuk: Why can't you measure seismic speed below 1.2 Hz.
    • Jan: Not clear, the method should work, it looks like there is a lot of variability around 1Hz, potentially different wave modes.
    • New point in the paper: evidence of the presence of body waves at 0.2 Hz, based on the speed measurement. Body waves seem to dominate on some days. In fact, it seems there is a continuous body wave background and on some weeks a stronger Rayleigh background overcomes it. Important for GW detectors.
    • Vuk: suggest to emphasize this to Victor and Gary via email, their response could help place this result in existing geo literature. ALso suggest to plot Fig 6 as a scatter plot, which should appear as -45 degree line.
    • Daniel: where would body waves come from?
    • Jan: not sure.
    • Jan: also have very good Wiener subtraction. Should we try a more visible journal, like Nature geophysics?
    • Vuk: worth considering, depends on what is known about body vs Rayleigh background. Also, it seems we don't need the depth aspect of this array is not needed for Fig 6.
    • Jan: correct, could try another array like Sweatwater.
    • Vuk: Could we use an estimate of Rayleigh wave speed from elsewhere? And plot lambda/4 on the Figure 5.
    • Ross/Pat: could try to estimate the speed from mining blast data. Pat working on this now, Ross did a study in the past.
    • Jan: Could use shear wave speed, which was measured, and convert based on some assumption on the poisson ratio. This could be a value for now, that could be updated later from other analyses.
    • Gary: could use the mine blasts. Have very solid data on shear wave speed from the active excitation at 2000. But this is on the scale 10-100m, but don't know it at a larger scale, but wouldn't expect it to very much. You can also get uncertainty on these velocity measurements.
    • Jan will send an email summarizing these results. We should discuss how to proceed via email, if necessary we'll schedule another call before the winter break…
  • Teleseismic EQs and near-surface scattering
    • Leads: Daniel, Victor
  • Time-variable velocity changes
    • Lead: Victor, not started yet
  • Very low frequency harmonics (Ross)
groups/homestake/meetings/20171208.txt · Last modified: 2017/12/08 13:19 by mandic