A self-consistent, continuous velocity field solution (black
arrows)
Shen-Tu et al. [1999] determined using GPS and VLBI data (red arrows) [Bennett et
al., 1999; Ma and Ryan, 1998; Thatcher et al., 1999]
Quaternary fault data [Jennings, 1994; Peterson and Wesnousky, 1994], and imposed
NUVEL-1A plate motion [DeMets et al., 1994].
Ellipses represent a 95% confidence limit. Blue dots represent seismicity
recorded from 1850-1998. (GV = Great Valley, B&R = Basin and Range,
CP = Colorado Plateau, SAF = San Andreas Fault, SN = Sierra Nevada,
GB = Great Basin). Longitude and latitude are given in degrees west
and north.

The minimal root mean squared deviatoric stress field
determined from GPE variations, calculated assuming Airy compensation
of topography. Different colors represent delta GPE values, sigma zz,
relative to a column of lithosphere at sea level. Tensional stress
are open white principal axes and compressional stress are black
principal axes.

Stress field boundary conditions. The analog
motion (open arrows) associated with these boundary conditions has
a PA-NA pole that is approximately 10 degrees west of the NUVEL-1A [DeMets et al., 1994] PA-NA
pole. Tensional stress
are open white principal axes and compressional stress are black
principal axes.

The total vertically averaged (over L=100 km) deviatoric
stress field that is the sum of stresses due to potential energy
variations (above) and plate interaction (above).Tensional stress
are open white principal axes and compressional stress are black
principal axes.

The self-consistent
flow field determined from strain rates calculated by scaling the
total stress tensor field (above) by the inverse of viscosity
(below) for all areas east of the San Andreas fault.

The total deviatoric stress field determined from the sum
of stresses due to GPE variations estimated using the filtered
GEOID96
and the corresponding best-fit stress field boundary conditions
associated with PA-NA plate interaction. Tensional stress
are open white principal axes and compressional stress are black
principal axes.

The vertically averaged effective viscosity (over L=100 km)
for the western US determined by dividing the magnitude of the total
deviatoric stress (above) by the magnitude of the strain rate
for each grid area determined from the self-consistent
kinematic model
Shen-Tu et al. [1999].

last edited 02/21/00 by L. Flesch