groups:homestake:meetings:20151015 [School of Physics and Astronomy Wiki]

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Homestake Meeting Minutes, 10/15/15

Attending: Gary, Ross, Daniel, Michael, Victor, Gwynne, Levi, Vuk, Tanner, Pat

Homestake wiki: https://zzz.physics.umn.edu/groups/homestake/home

Our agenda:

  - Homestake array status: 
    - Tanner: computer was down for 2 weeks almost (since Sat Oct 3). Interacted with Jaret, resolved yesterday. Fixed the missing default route, currently on DHCP not fixed IP. The computer was not collecting data since it did not have the IP. Should be getting the data now, Tanner will check. Gary: have to check the routing, if there is another machine with the same IP. Data not transferred to UMN yet since the IP has changed (since Oct 5, probably the reboot happened then). Should try to fix the IP (i.e. return to the old fixed IP), but not sure if we can do this remotely. Jaret may be able to help us with it. Tanner will try to deal with this today.
    - Gary has Baler data from the last visit, will bring it to UMN. It looks like all remote stations were ok. The station in the town might have a problem, instabilities, not on bedrock. Good that we put Guralp in this station. We'll see in the spring. Victor and Daniel will bring some disk to copy this data.
    - Gary has data from several nearby stations, withing few hundred miles. Will bring this data too. Can get blasts from coal mines from Nebraska etc.
  - Update on activation experiments:
    - Gary: accomplished what was intended. Took all data we wanted on the surface, and did two experiments with 9-component survey experiment on 4100 and one on 4850 - this is to measure anisotropy, for source started with a sledge hammer then switched to sliding weight (jackhammer). Make 3 shots in 3 directions, in principle can sort out anisotropy. Know no such experiment where both source and receiver are in an anisotropic rock, the analysis will be new. Also did a reflection experiment with a streamer on 2000 level, but the source was too small to see a reflection from 2000 feet away. Have a 100-fold stack, hopefully folding will help. Ross is starting to look at this now. Keeping track of the geometry of the source and receiver will be hard, probably have ~3000 shot points, so very tedious.
    - Heard from Lee: accelerometer that was used to measure the timing of the active surface shot did not work. This will complicate the analysis, but expect to be able to manage since the data is good. Have GPS times from Lee, may be useful, have to still look at it... 
  - data analysis updates
    * analysis updates
    * planning for data analysis workshop, Oct 23-25 (Fri-Sun) at UMN.

Proposed topics for the data analysis workshop:

  - A session to talk out what each group's broader goals with background to make sure we all understand each other. Two options: (a) have people give talks on specific topics, or (b) open discussion  with prompting questions. Gary recommends a hybrid were a couple of us give short presentations with linked discussions. Topics might be:
    - Teach seismologists some basics of gravitational waves, how GW detectors work, and why seismology is relevant.
    - Teach physicists some basics of seismic wave propagation to your students.   Here is a list of some items that are clearly relevant:   P and S body waves in isotropic media, Rayleigh and Love waves, anisotropic media basics (velocity dependence on direction, shear wave splitting, and particle motions in an isotropic medium), and the free surface interaction in isotropic and anistropic media.
    - These are probably best done the context of what our broad science goals are.
  - Gary has some analysis code under development to show.  These are tools to visualize and measure three-component particle motions.
  - We need to give an overview of the active source data and any preliminary results we can show by then.
  - Gary started an event catalog for the experiment.  It needs some tuning, but Gary can show the group what he has.
  - Ross looking at the coupling of solar wind modes into Earth modes, could be observed in quiet stations.
  - Daniel can discuss his work on earthquakes. Will bring slides/pictures. 
  - instrument calibration - can be done remotely, could try to do it during the workshop
  - What do we know about velocity (vs depth, vs direction) - this is linked to your active source study
  - Wiener filter study - this is pursued by Michael Caughlin and Jan Harms, and neither will be present. Maybe we can ask them to connect remotely
  - estimating the composition of the seismic noise. This would include the algorithm we are developing, maybe some simulations and applications to data. It should also include using some of the other algorithms from geo-community. Related to this is also understanding the Rayleigh waves better - how their amplitude depends on depth, P-vs-S content etc. I am sure learning for geophysicists would help us a lot here...
  - Extending the life of the array?
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