Geodetic velocity field for stable North America
(September 2005)

Horizontal velocities at continuous GPS sites in the Central and Eastern U.S. with respect to rigid North America, defined by estimating a rigid rotation based on all continuous GPS sites on the North American plate east of longitude 100W (to avoid tectonic deformation from the Western U.S.) and more than 2100 km away from the post-glagial rebound (or GIA) center (to avoid crustal deformation due to glacial isostatic adjustment).

These velocity appear to follow a random pattern. However, spatial filtering (see below) reveals a spatially coherent pattern most likely to result from post-glacial rebound.

Black arrows: Spatially averaged horizontal velocities calculated using a nearest neighbor scheme with a search radius of 800 km. The dashed circle has a radius of 2100 km and is centered on the post-glacial rebound uplift (star). A solid circle with a 800 km radius is shown to illustrate the search radius dimension.

Background: Interpolated vertical velocities. Only sites with random-walk noise magnitude < 1 mm/sqrt{yr}, category A sites, and sites with velocity standard deviation less than 1.5 mm/yr are used. The interpolation scheme uses an adjustable tension continuous curvature surface gridding algorithm with a tension factor of 0.9.

SINEX files:

  1. Combined solution (in ITRF2000)
  2. GIPSY-OASIS sinex (loose)
  3. GAMIT-GLOBK sinex (loose)

PSVELO files:

  1. Combined solution (in ITRF2000)
  2. Combined solution (in NOAM frame)