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Homestake Meeting Minutes, 07/27/17

Attending: Pat, Andrew, Daniel, Ross, Victor, Vuk


  • Next Meeting: Aug 24.
  • Data analysis topics
    • Data corrections, frame production (Gary/Daniel/Pat)
      • Pat: Frames ready at Caltech.
      • Daniel: Some timing hiccups, especially when a station is reset, timing off by 1/4 of a second. Have to chase it further, may be ignorable. Doesn't happen often. We could flag the times/stations when this happens. (See also below)
      • Don't know if IRIS updated the data yet, should check with Gary…
    • Event catalog (Gary/Ross)
    • Radiometer updates (Pat, Andrew)
    • Parameter estimation for Rayleigh and Love (Pat) - pdf
      • Velocity estimate is close to the local phase velocity, estimated using local displacements as a function of depth.
      • Homogeneous half-space is not a good approximation, don't get good fits to the depth data.
      • H/V ~ 1.3 - Victor: this is normal/common.
    • Teleseismic events and Wiener filtering (Daniel, Michael)
      • Vuk: making progress, will try to present at the next meeting.
    • Very-long-periods (Ross) - pdf, pptx
      • Putting a paper together. Large section written up. Expect to circulate it in a month or so.
      • Next try to remove tides alone, see how that affects the data.
    • Velocity from noise correlations (Daniel): pdf
      • see timing glitches at some times.
      • Pat: seems to be related to bad timing, maybe due to network problems.
      • Ross: may be an issue with the 800 station, had a large number of mass re-centerings.
      • Daniel: Also see slow drifts in RRDG, know that we lost the clock in this station towards the end of the run.
      • Find time-shift between two stations to match the waveforms, this gives the group velocity. Do it for each station pair individually, works well for some cases and not for others.
        • Similar to Pat's analysis, but using the noise instead of transients.
      • Concern regarding uncertainty for station pairs that are close in horizontal plane. Maybe not seeing Rayleigh waves, will follow up on this.
      • Results in velocity estimates and eigenfunction profiles. Can compare to Pat's approach.
      • Vuk: Maybe we can combine these measurements with Pat's and do model selection for eigenfunctions.
        • Victor: there are many models out there, may have to constrain them a bit before launching into it.
      • Gary: active data may also constrain these, some of the models are definitely not supported by the data.
      • Daniel, Ross, Gary, Pat: will try to pull together all velocity measurements to start making comparisons. Pat will send the link again.
  • Papers
    • Homestake Array Summary paper: pdf
      • Leads: Vuk, Gary, Victor
      • target: Seism. Research Lett., 6000 words, 10 figures.
      • Gary almost done with updates in the paper.
      • Vuk will send it for internal LIGO review when Gary is done. No objections to this plan.
  • Active excitation overview paper
    • Leads: Gary, Ross
    • Others: Victor, Daniel,…
    • Will discuss at the next call.
  • Surface Active Excitation
    • Leads: Victor, Boise
    • Others: Gary, Ross
    • Victor talked to Lee - they are planning a more general paper on H/V etc, will include the landstreamer data in it. Timeline: next couple of months to write it up. Happy to have input from us.
    • Vuk: it seems this would be decoupled from any papers we want to pursue.
    • Gary/Victor: Agree.
    • Vuk: let's invite them to give us a presentation in a couple of months, when they are ready.
  • 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
    • Novel, but maybe insufficient for a publication. Could use the eigenfunction measurement for Rayleigh and assume something about Rayleigh field to make preliminary estimates of the Newtonian noise.
  • Estimating directional and modal composition of the seismic noise. (Pat, Levi, Vuk)
    • Leads: Pat, Vuk, Levi
  • Wiener filter application
    • Leads: Jan, Michael
    • Aim for late August.
  • 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/20170727.txt · Last modified: 2017/07/27 12:30 by mandic