by Corné Kreemer, William C. Hammond, Geoffrey Blewitt, Austin A. Holland, and Richard A. Bennett
This map presents a model of crustal strain rates derived from Global Positioning System (GPS) measurements of horizontal station velocities. The model indicates the spatial distribution of deformation rates within the Pacific–North America plate boundary from the San Andreas fault system in the west to the Basin and Range province in the east. As these strain rates are derived from data spanning the last two decades, the model reflects a best estimate of present-day deformation. However, because rapid transient effects associated with earthquakes (i.e., postseismic deformation resulting in curvature of the GPS time-series) have been removed from the GPS data, these strain rates can be considered representative of the interseismic, steady-state deformation associated with the accumulation of strain along faults. This model is useful for both seismic-hazard and geodynamic studies to understand the activity rates of (known and unknown) faults and the plate tectonic boundary and buoyancy forces that cause the deformation, respectively. In more slowly deforming areas we expect fewer, smaller earthquakes and infrequent large earthquakes will have a much longer recurrence time compared to those in rapidly deforming areas.
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Map 178, one 48×46-inch color plate; scale 1:1,500,000; rolled only; $46.00
Map 178a, one 48×46-inch color plate printed at 91% of original size to fit on 44×42-inch paper; original scale 1:1,500,000; rolled or folded; $18.00