We use GPS-observed velocities of 91 campaign and continuous stations throughout the southern Illinois basin and the New Madrid area to derive kinematic block models of the U.S. midcontinent region. The inversion procedure utilizes the observed velocity field to obtain block velocity/rotation rates, fault-locking strain, and internal block deformation. In these figures, the observed and predicted velocities based on the two- and four-block models (bounded by vertical faults) are shown, plotted in the Stable North American Reference Frame (SNARF). The observed velocity field from 1997 to 2008 shows an average ~1-2 mm/yr northward trend. A table that summarizes the observed velocity vectors, component sigmas and correlation is included, along with another table that summarizes the principal strain rates obtained from the different models.
Figure S1. GPS velocities of the two-block model plotted with respect to the Stable North American Reference Frame (SNARF). Black arrows with 95% error ellipses = observed velocities; gray arrows = predicted velocities.
Figure S2. GPS velocities of the four-block model plotted with respect to the Stable North American Reference Frame (SNARF). Black arrows with 95% error ellipses = observed velocities; gray arrows = predicted velocities.
Table S1. Observed GPS station velocities used in this study (with respect to station BLO1).
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Table S2. Principal strain rates for the different block models.
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