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April 26, 2013 CIET Minutes

 

CIET Conference Calls

 

 

Agenda

    a) instrument performance during CI and recent cruises.
    b) implications of instrument performance for 2013 deployments in the Cascadia region.
    c) fall back options for 2013 deployments in the event that we continue to see significant instrument problems.

Participants

Maya, Dean, Susan, Rick Carlson, Emilie, Doug, John, Anne, Jeff McGuire, Brent Evers, William, Greg Anderson
Missing: Donna, Richard

Minutes   

AGU Special Session

    Emilie put a proposal in with Susn, Anne, and Richard
    Haying Gao and Yang Shen have a similar session proposal in
    These may be combined by AGU.

OBS workshop

    William working on this with Harm van Avendonk

LDEO issues

Maps and Tables

Pages from OC_Oct_2012_LDEO.pdf
Year2_Yr1depl_20120424_drt
CIET_Year3_deploybyOBS.pdf
CIET_Year3_deploynoLDEO.pdf

 30% failure for CIET Year 1

Thought to be due to rough handling - cables pulled out and corrosion.
Also possible timing issue on the APG - misaligned by minutes rel to Z channel. 
APGs dominated by instrument noise above 2 Hz, so not useful for high freq

Recent Trehu cruise in Chile - 

No instruments from LDEO recorded on the trillium compacts.  
There was data on the older instruments.  
Timing issue on the APGs.  Problem on APGs was seen and realized that this would be a problem on Anne's already deployed instruments in Chile.  CIET instruments still recorded something, but Anne's did not.  This is not understood. Current CIET Year 2 LDEO instruments should have fixes in place for most of these problems.  

Should consider instrument issues and come up with different options. If this problem is still seen in the recoveries this summer, can the problem be fixed before the deployments? 30% failure rate is a long term average of how OBSs perform for longterm experiments.  If there is a large # that have problems, do we want to consider not putting any LDEO OBSs down?

Year 3 deployment - 30 are LDEOs and 20 TRMs.  Many are focused at Gray's harbor.
Could not deploy any LDEOs in Year 3 and find 10 OBSs to fill holes away from Gray's harbor. 
Possibility of redoing Gray's harbor when there is a greater likelihood that the instruments work.
If Nabalek deploys broad bands on the Atlantis cruise, there are no BB OBSs left in the pool to fill the holes that would be left in this case.

Description of data issues with the APGs.  

Email from Anne
APG timing:
There is something wrong with the timing on the APGs for yr 1.  Here is a screengrab showing HHZ and HDH from Cascadia yr 1 for a earthquake in the Japan trench.  The best S/N is on J42A.  We also observe timing lags or delays of minutes relative to LDEO-standard OBS in the Chile data, although we are not able to compare APG to Z for those data.  For Chile, total clock drift is small, and I hope that the source of this problem can be identified and fixed soon.  I also noticed that although these APG data are listed in SeismicQuery  as being available, they were not included in a breqfast request I made this morning.  I got these data from John, who had requested them earlier.

APG high frequency response:
The second screengrab shows T-phases from a regional event (2-25 Hz).  No signal on the APGs above 2 Hz.  We also observe this in the Chile data.  The 3rd shows spectra for the data in figure 2.   APGs have a steadily increasing noise floor for frequencies above 2 Hz.
Andrew found the timing error.  Script with an error was used by the Navy.
 

SIO issues

SIO timing issues? IRIS received a plan and expected corrected data on 19th April.
Quality of shallow water data
Anne: all DPGs have very variable signature.  John: response varies greatly with water depth
Susan: has a student looking for microseisms and she can examine the quality of the SIO Abalones
 

Cruise Options

Nabalek cruise being delayed and potentially becoming part of Atlantis recoveries.  Recover CIET 1st and then go south and deploy Nabalek instruments from the Atlantis.
Brent: setting some instruments aside from Nabalek to be deployed later? He thinks that there should be 9 SIO BBs that are unused during the next year.
Oceanus cruise in Sept will be very full and probably not accommodate the LDEO instruments.  They are coming back to the dock once and could come a second time. (i.e. another cruise).  But the people scheduled after this leg are unwilling to move back.
William: The cruise following on the Oceanus could go on the Thompson.  Currently scheduled student cruises could move.

How does CIET summarize any data issues that are out there?

How can we get feedback on any data issues that are out there before the discussion in 2 weeks?
URI poster at SSA meeting using long period data from CI.
send out some emails

What to do about timing issues

Notes above on timing issues on SIO and LDEO APGs
IRIS send out an email?
IRIS quarantine the data?  
For SIO it was across channels and so quarantining the data made sense
For LDEO it is on the APG only because of difficulties in doing this.  But the seismometer data is correct and should not be quarantined.  Quarantine just one component - this might already be implemented.
Anne is concerned that channels are showing up but then not being delivered from the BRQFST request.
Anne will discuss this with the IRIS DMC and will send an update.