While most of the seismicity in the U.S. is obviously concentrated along the North
American-Pacific plate boundary, there is also a significant seismic hazard in the New Madrid
Seismic Zone, where three earthquakes of magnitude greater than 7.5 occurred in 1811-1812.
Using triangulation from the 1950's and GPS in the 1990's, Liu et al. [1992]
found maximum horizontal shear strain of
, which is a third of the strain reported
across the San Andreas fault system [ Thatcher, 1991]. Seismic hazard in western Washington
was addressed by Savage and Lisowski [1991 a]. They used trilateration data to estimate
convergence between the North American and Juan de Fuca plates. The geodetic estimates find
convergence at an azimuth of 
, which is in good agreement
with NUVEL-1 direction of 
.
Their model suggests a locked segment with slip deficit equal to the plate convergence rate, 40
mm/yr.
The broad scale features of deformation in Alaska were established by mobile VLBI experiments conducted in the 1980's [ Ma et al., 1990]. In the past four years, no additional large-scale results have been published, although there have been several smaller scale experiments. Savage and Lisowski [1991 b] confirm that within measurement uncertainties no right lateral shear is accumulating along the Denali Fault, which contradicts the Holocene record which predicts 10-20 mm/yr. Larson and Lisowski [1994] combined trilateration and GPS measurements collected over a 10 year period to confirm a lack of strain accumulation in the Shumagin gap zone. Both these results are consistent with low seismic hazard in these regions.