Horizontal Velocities in the Central and Eastern United States from GPS Surveys during the 1987-1996 Interval

摘要

The National Geodetic Survey and the Nuclear Regulatory Commission jointly organized GPS surveys in 1987, 1990, 1993, and 1996 to search for crustal deformation in the central and eastern United States (east of longitude 108 degees W). We have analyzed the data of these four surveys in combination with VLBI data observed during the 1979-1995 interval and GPS data for 22 additional surveys observed during the 1990-1996 interval. These latter GPS surveys served to establish accurately positioned geodetic marks in various states. Accordingly, we have computed horizontal velocities for 64 GPS sites and 12 VLBI sites relative to a reference frame for which the interior of the North American plate is considered fixed on average. We also computed horizontal strain rates for the cells formed by a 1 percent by 1 percent grid spanning the central and eastern United States.