Homestake Meeting Minutes, 05/05/16

Attending: Daniel, Ross, Gary, Vuk, Victor, Tanner, Pat

Agenda:

• Homestake array
  • update from Pat and Terry's visit: Pat and Terry visited all stations except RR. Swapped Yates twice, there should be 24 backup directories at Indiana and Minnesota. Yates still having telemetry issues, but the baler should be working fine. At WTP the telemetry is a bit better, but the problem is not completely solved. Added some insulation (mulch bags) to some of the surface stations. Everything in good condition.
    • Vuk: do we lose data from Yates/WTP, or just telementry? Pat: not sure. Daniel: look ok.
    • Pat: DEAD not working most of the winter, probably poor solar pannel.
    • Gary: looking at the balers, everything looks fine except for DEAD station (probably lost ~1/2 of the time). The sensor seems fine, the data appears to be OK when it is recorded. Hopefully summer will be better.
    • Gary: working on merging the baler and online data. Had to fix data naming etc, creating data into day-files, easier to manage the data. Started transferring data to IRIS.
    • Daniel: the day-files in miniSEED format should work fine for them.
    • Tanner: should be straightforward to convert these files into frames.
    • Gary: probably easiest to make a DUGL account on a local machine, and let Daniel and Tanner know where it is to copy the merged data to UMN and Caltech.
  • status of stations
    • Daniel: some odd repetitive spiky signals from LHS.
    • Victor: might be real.
    • Gary: Looks like high-freq transients, could be due to human effects. Transients on all channels, high-frequency content, like footsteps.
    • Gary: Gain was changed on B4850. Need to correct for the amplitude gain (32x higher).
    • Tanner: showed some PSDs for this station, don't see significant difference due to the increased gain.
    • Victor: do we rail for loud signals?
    • Gary: looked at the Ecuador EQ, did not see it clip…
    • Tanner: there are other even louder signals that do not clip.
    • Gary: probably best to leave 4850B alone, just to avoid making more changes in metadata.
  • rough planning for the next visit to extract surface stations.
    • Gary: could get away with 3 people to do this, and goes fast (4/day). Should check with SURF whether they want us to take out the vaults. Vuk to check with Jaret.
    • Gary: concrete can be usually left in. Taking the post out could be difficult.
    • Vuk/Gary: RR, LHS, 3 outer sites have to be cleaned out completely.
    • Gary: no need to do another baler swap until the end of the data acquisition. But we want to extract the baler data.
    • Gary: should ask PASSCAL whether we should do a partial return.
    • Availability: Gary ok in late september, Pat OK, Ross OK (not sure), Daniel has one conflict (will follow up), Vuk should be OK (teach).

• data analysis updates
  • Rayleigh waves https://zzz.physics.umn.edu/_media/groups/homestake/meetings/2016_05_04_rayleigh_waves.pdf
    • Victor: Rayleigh and Love waves come roughly at the same time, so this may complicate the recovery. Could try to separate them in time since they travel at different speeds.
    • Tanner: for nearby events it would be harder to separate Rayleigh and Love.
    • Victor: yes, but also you lose high-frequency part of the signal from very distant events.
    • Victor: the noise field probably also have significant Love waves (SH waves), may have to model this too. In the microseism, we expect the Rayleigh to be stronger, at higher frequencies this might not be true.
    • Ross: do_mft program, part of the computer programs for seismology: http://www.eas.slu.edu/eqc/eqccps.html. Useful for this kind of studies.
  • Victor: there will be a couple of students processing the active source data, one at Boise state and one visiting student at Caltech.