Homestake Meeting Minutes, 04/13/18

Attending: Gary, Pat, Victor, Vuk, Daniel

Agenda:

• Next Meeting: May 11
• Data analysis topics
  • Data corrections, frame production (Gary/Daniel/Pat)
  • Event catalog (Gary/Ross)
  • Radiometer updates (Pat, Andrew) {{:groups:homestake:meetings:rwave_pe_and_radiometer.pdf|}}
    • Pat: eigenfunctions measured above 0.2 Hz, not much signal below it. Gary agrees.
    • Vuk: Correction of equation on slide 6.
    • Daniel: for data points where there is a binary distribution (some retro and some pro), should we try to force the retro solution? This could change the mean and the median.
    • Pat: not sure, had the same question. Will follow up via email.
    • Victor/Daniel: if v(f) is a power law, then the coefficients of the biexponential eigenfunctions are independent of frequency.
    • Pat: velocity at low frequencies is maybe not modelled well with a linear or a power law. Maybe there are better choices?
    • Victor: usually people don't fit velocity vs frequency with a parametrized curve, instead they use their data (or don't use some frequencies).
    • Victor/Pat: could try to fix velocities from other estimates, and only estimate other parameters
    • Vuk: it seems posteriors and priors are similar, not constraining the eigenfunctions more than we already did before the measurements.
    • Victor: yes, the paper could simply state that the data is consistent with the model.
    • Vuk: Maybe we can get away with some simpler statistical statement, showing that the model is consistent with the data?
    • Victor: would be nice, but would not be the selling point of the paper.
    • Vuk: let's then proceed with what we have. If we come up with a simple statistical test we can add it…
  • 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.: Still waiting. Vuk to check with the editor…

• Active excitation overview paper
  • Leads: Gary, Ross
  • Others: Victor, Daniel,…
  • Draft.

• 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: Draft.
  • Michael: draft produced after discussing with Victor. Will iterate again to make it more suitable for geophysics community. Moved text around to emphasize geo aspects more. Target: Journal of Geophysical Research: Solid Earth. Physics implications are in the conclusion only.
  • Victor: this is the standard journal for geophysics research, so the emphasis should be on geophysics. It is OK to add on implications for physics.

• Teleseismic EQs and near-surface scattering
  • Leads: Daniel, Victor

• Time-variable velocity changes
  • Lead: Victor, not started yet

• Very low frequency harmonics (Ross)
• 3D PDF of Homestake geometry - draft for active source experiment paper homestakeexperiment.pdf