[unav_all] High-Rate Geodetic Data from UNAVCO and Other Community Data Centers

David A. Phillips dap at unavco.org
Thu Jun 19 21:14:32 MDT 2014


Dear Colleagues,

Inspired by Joan Gomberg's excellent presentation at the 2014 IRIS Workshop on "Exploring Pragmatic to Esoteric Applications of PBO High-Rate Geodetic Data to Constraining Fault Slip" we would like to take the opportunity to highlight the availability of high rate geodetic data products and services available from UNAVCO and other geodetic data centers.  A brief summary is provided below with additional information and data access available from www.unavco.org.

*** GPS ***

The "standard" sample rate for PBO GPS data is 1 sample per 15 seconds.  "High rate" GPS data include 1-sps (1 Hz) and 5-sps (5 Hz) sample rates.  Most PBO GPS receivers use ring buffers to store several weeks (1 Hz) or several days (5 Hz) worth of high rate data.  High rate GPS data are considered "custom" datasets and are not archived continuously from most stations due to cost and infrastructure constraints.  Custom high rate datasets can be requested by PI's using the following custom data request form:   http://www.unavco.org/data/data-help/custom-data-request/custom-data-request.html

A special case is that high rate GPS data sets are automatically collected following significant geophysical events.  Examples of recent earthquakes that we downloaded high rate (1- and 5-sps) data in response to include the 2014-03-10 M6.8 Ferndale, CA event and the 2014-04-01 M8.2 Iquique, Chile event and M7.7 aftershock.  The M8.2 Chile response is significant in that it was a full network download. That is, rather than stations within a certain radius of the epicenter, we acquired high rate data from all available stations within the PBO and COCONet network footprints. As a result, data from 1,102 stations at 1-sps and 785 stations at 5-sps are now available to the community for the time period of the main shock and aftershock. Full network downloads are only performed in special cases, and can be requested using the above form. Resources to download and archive large scale high rate datasets can be requested as part of an investigator-driven RAPID proposal or collaboration. 

Another special case is that 1-sps GPS data are continuously archived from 282 real time streaming stations in the Pacific Northwest that were part of the NSF-ARRA Cascadia Upgrade project.  Real time streaming data are discussed further below.

All archived high rate GPS data, whether acquired as part of a custom request, an event response, or from streaming stations, are available as unprocessed Level 1 RINEX files. The direct link to the high rate GPS data FTP site is:

	UNAVCO GPS high rate data, unprocessed RINEX files: ftp://data-out.unavco.org/pub/highrate/

Additional GPS data search and access methods are described at http://www.unavco.org/data/gps-gnss/data-access-methods/data-access-methods.html.

Standard rate (1 sample per 15 sec) data from 1800+ GPS stations from the PBO, COCONet (and soon TLALOCNet), SCIGN, NGS CORS and other networks are processed routinely by the GAGE Analysis Centers at NMT and CWU and AC Coordinator at MIT to generate Level 2 processed products (24-hour daily position solutions, station time series, station velocities, SINEX and ancillary files). As a service, data from additional stations can be added to this analysis stream; please contact us for details. The GAGE ACC/AC's are managed by UNAVCO via subaward. Note: we currently recommend only using Level 2 processed products generated by the NMT Analysis Center for time periods prior to January 2013. The CWU and combined PBO solutions currently (temporarily) contain height anomalies that are actively being fixed and which will likely be resolved by end of July 2014. The NMT solutions are not affected by this issue. Processed GPS products are available from the UNAVCO archive using the links below. 

	UNAVCO GPS data products main download site: ftp://data-out.unavco.org/pub/products/
	UNAVCO GPS site position time series files: ftp://data-out.unavco.org/pub/products/position/
	UNAVCO GPS site velocity files: ftp://data-out.unavco.org/pub/products/velocity/
	UNAVCO GPS site coseismic offsets: ftp://data-out.unavco.org/pub/products/event/

UNAVCO also provides low latency (<2 s), high rate (1-sps) "real time" streaming data from 440 GPS stations, primarily from the PBO and COCONet networks but also from ~30 NOAA stations in southern California and 8 USGS stations in Yellowstone. In addition to unprocessed observables, we also now stream PPP solutions for all stations using Trimble PIVOT RTX software.  Also, through a separate NSF award (ES and IF programs) to SIO and UNAVCO, ~15 RT-GPS stations in Southern California have been augmented with MEMS accelerometers and geodetic module upgrades that will synchronize the GPS and accelerometer data and estimate seismogeodetic displacements and velocities in order to facilitate studies producing very broad band waveforms to support earthquake hazard studies.  

	UNAVCO Real Time GPS data stream access: send an email to rtgps at unavco.org to request access
	UNAVCO Real Time GPS data information: http://www.unavco.org/data/gps-gnss/real-time/real-time.html
	UNAVCO Real Time GPS network information: http://www.unavco.org/instrumentation/networks/real-time-gps/real-time-gps.html

Processed high rate GPS data products are available from other community data centers as well including the Nevada Geodetic Laboratory at the University of Nevada Reno, the Pacific Northwest Geodetic Array (PANGA) at Central Washington University, and the Scripps Orbit and Permanent Array Center (SOPAC) at UC San Diego:

	UNR GPS data products main page: http://geodesy.unr.edu
	UNR Rapid GPS 5 minute solutions (1-day latency): http://geodesy.unr.edu/NGLStationPages/RapidStationList
	UNR Ultra Rapid GPS 5 minute solutions (1-hour latency): http://geodesy.unr.edu/NGLStationPages/UltraStationList

	CWU GPS data products main page: http://www.geodesy.cwu.edu/
	CWU Real Time GPS Measurements: http://www.geodesy.cwu.edu/realtime/  

	SOPAC main page: http://sopac.ucsd.edu/other/sopacDescription.html
	SOPAC GPS data products: http://sopac.ucsd.edu/processing/
	SOPAC High Rate GPS data: ftp://garner.ucsd.edu/highrate/
	

*** BOREHOLE STRAINMETERS, SEISMOMETERS, PORE PRESSURE ***

High rate (1-sps) processed data sets are generated automatically following any event of interest both in the PBO area and worldwide. Also, 1-sps processed data are available for any time-window as the same custom data request form linked above. 

All PBO strainmeters are collocated with seismometers. Several sites also have 1-sps pore pressure sensors. These data are available in real time for the IRIS DMC.

Unprocessed and processed borehole geophysics data are available from the UNAVCO archive as described here:
	http://www.unavco.org/data/strain-seismic/strain-seismic.html.


*** SHORT COURSES, WEB SERVICES AND MORE ***

UNAVCO offers short courses for GPS and Strainmeter data analysis. Strainmeter short courses, offered on a near yearly basis, these courses cover the theory of strain, how strainmeters work, data processing and access. The most recent course, in March 2014 had ~40 participants.

UNAVCO is also developing a suite of web services to facilitate access to high rate geodetic data products. Many of these web services provide direct integrated access to both UNAVCO and IRIS data products.  Because we are about to roll out significant updates to existing web services and introduce new services, a separate and more detailed communication regarding web services will be circulated in the near future.

Please feel free to contact us if you have any questions or would like additional information.  We also stand ready to help foster new and expanded collaborations between members of the geodetic and seismic communities.

Thank you and kind regards on behalf of Meghan Miller, Chuck Meertens, Glen Mattioli, Kathleen Hodgkinson, David Mencin and myself,

David

--
David A. Phillips, Ph.D.
  Project Manager, Geodetic Data Services
  UNAVCO
  6350 Nautilus Drive, Boulder, CO 80301
  Tel: 303-381-7471, Fax: 303-381-7451
  phillips at unavco.org
  www.unavco.org

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