US Pacific Northwest GPS

GPS studies of the US Pacific Northwest at RPI

Rob McCaffrey, Charles Williams, Ani Tikku
RPI Students: Peter Zwick, Colleen Stevens, Ellen Robey, Paul Wallenberger, Cathleen Donovan, Albert Nummelin, Cheryl Johnson, Maureen Long, Jesse Vollick, Anna Smith, Kristin Fixx, Jake Schowalter, Karin Lackmann, Jackie Krajewski, Jon Ganz, Andy Ratigliano, Emily Witthaus*
Volunteers (other than RPI): Cheryl McCaffrey, Beth Walton, Marc Nabelek+, Hanya Zwick+, Peter Arlein+, Michal Zwick+, Chris O'Brien+
Collaborators: Tony Qamar (UW), Herb Dragert (PGC), Bob King (MIT), Giovanni Sella (Northwestern), Todd Williams (Humboldt State)
* - undergraduate students, + - highschool students

We are monitoring geodetic motions in the US Pacific Northwest to estimate locking on the Cascadia subduction zone, upper plate strain, and the motion of Oregon relative to North America. In collaboration with Oregon State University we occupied the network between the coast and Sisters OR at the latitude of Corvallis in June 1996, June 1997, August 1998, and August 1999. This region was originally surveyed by the USGS in 1992 and 1994. In 1999 we extended the network (click here) northward to the Portland region. In 2000 (click here) we occupied sites in eastern Oregon and collobarated with the University of Washington to re-occupy sites in western Washington State. In 2001 (click here) we occupied sites in northern Oregon and collobarated with the University of Washington to re-occupy sites in Washington State and with the Pacific Geoscience Center (Geol. Survey of Canada) to establish GPS sites in SW British Columbia.

We are also re-processing data collected by the USGS, Cascades Volcano Observatory, and National Geodetic Survey to include in our velocity solution.

Also with OSU, we are running RPI Ashtech receivers continuously at Corvallis (CORV) (Photo and Log file) and Newport (NEWP) (Photo and Log file).

Oregon vectors file (from McCaffrey, 2002).

Velocities of Pacific Northwest continuous GPS sites. We process regional continuous network data using GAMIT/GLOBK.

Sources of continuous site GPS data:

OSU FTP site for rinex data (CORV and NEWP only)
Scripps SOPAC archives of rinex data (Contains global rinex data)
CWU archives of rinex data (Contains all PANGA data)

Some maps:

2004 campaign.
2003 campaign.
2001 campaign map and site coordinates.
2000 campaign map and site coordinates.
1999 campaign map and site coordinates.
1998 HARN campaign map.
Preliminary campaign results for 1992-1999.5 in North American reference frame.
Preliminary campaign results for 1992-1999.5 with Oregon block rotation removed.
Map of geodetic sites in Pacific Northwest occupied by several groups
Shaded map of northward velocities of geodetic sites in Oregon.

Field photos:

1996 field photos taken by R McCaffrey
2004 field photos

Publications and reports to date related to Oregon and Cascadia:

McCaffrey, R., and C. Goldfinger, Forearc deformation and great subduction earthquakes: Implications for Cascadia offshore earthquake potential, Science 267, 856-859, 1995.
McCaffrey, R., Influences of recurrence times and fault zone temperatures on the age-rate dependence of subduction zone seismicity, J. Geophys. Res., 102, 22839-22854, 1997.
McCaffrey, R., M. D. Long, C. Goldfinger, P. C. Zwick, J. L. Nabelek, C. K. Johnson, and C. Smith, Rotation and Plate Locking at the Southern Cascadia Subduction Zone, Geophysical Research Letters, vol. 27, no. 19, p. 3117-3120, October, 2000. ( PDF reprint , vectors file, and maps of velocities from that paper.)
Williams, C. A., and R. McCaffrey, Stress rates in the central Cascadia subduction zone inferred from an elastic plate model, Geophysical Research Letters, in press, 2001.( PDF preprint )
McCaffrey, R., A. Qamar, Z. Ning, M. Long, and C. A. Williams, US Pacific Northwest GPS Velocity Field Inferred from Campaign Measurements: Evidence for Large-scale Rotation and Plate Locking (abstract), AGU Fall 2000. Download PDF file of poster
McCaffrey, R., Crustal block rotations and plate coupling, in Plate Boundary Zones, S. Stein and J. Freymueller, editors, AGU Geodynamics Series 30, 101-122, 2002. (PDF, Oregon vectors file).
Recent abstracts are available on-line.
2000 NEHRP final report.
2001 NEHRP final report.
2003 NEHRP final report.

For addtional information, send e-mail to Rob McCaffrey (mccafr@rpi.edu).

More information about Oregon tectonic studies can be found at the OSU Marine Geology and OSU Geophysics homepages. Also available on-line is information about the GPS method.

Other Pacific NW regional GPS networks and data sources:

Bay Area Regional Deformation Network
Cascades Volcano Observatory
Central Washington University
Geological Survey of Canada (Western Canada Deformation Array)
National Geodetic Survey CORS network
Oregon - Washington NGS site
University of Washington
US Geological Survey

This work is funded by the US Geological Survey and National Science Foundation.