We describe a model for Caribbean plate motion based on GPS velocities of four sites in the plate interior and two azimuths of the Swan Islands transform fault. The data are well fit by a single angular velocity, with average misfits approximately equal to the 1.5–3.0 mm yr−1 velocity uncertainties. The new model predicts Caribbean‐North America motion ∼65% faster than predicted by NUVEL‐1A, averaging 18–20±3 mm yr−1 (2σ) at various locations along the plate boundary. The data are best fit by a rotation pole that predicts obliquely convergent motion along the plate boundary east of Cuba, but are fit poorly by a suite of previously published models that predict strike‐slip motion in this region. The data suggest an approximate upper bound of 4–6 mm yr−1 for internal deformation of the Caribbean plate, although rigorous estimates await more precise and additional velocities from sites in the plate interior.

[1] Geodesy can be used to infer long-term fault slip rates, assuming a model for crust and upper mantle rheology. We examine the sensitivity of fault slip rate estimates to assumed rheology for the Agua Blanca and San Miguel-Vallecitos faults in northern Baja California, Mexico, part of the Pacific-North America plate boundary zone. The Agua Blanca fault is seismically quiet, but offset alluvial fans indicate young activity. Current seismicity is confined to the nearby San Miguel-Vallecitos fault, a small offset fault better aligned with plate motion. GPS measurements between 1993 and 1998 suggest that both faults are active, with a combined slip rate of 4-8 mm yrÀ1 regardless of rheological model. However, slip rate estimates for the individual faults are sensitive to assumed rheology. Elastic half-space models yield 2-3 mm yr À1 for the Agua Blanca fault, and somewhat faster rates for the San Miguel-Vallecitos fault, 2-4 mm yr À1 , with uncertainties of about 1 mm yr À1. Models incorporating viscoelastic rheology and seismic cycle effects suggest a faster slip rate for the Agua Blanca fault, 6 ± 1 mm yr À1 , and a slower rate for the San Miguel-Vallecitos fault, 1 ± 1 mm yr À1 , in better agreement with geological data, but these rates are sensitive to assumed rheology. Numerical simulations with a finite element model suggest that for similar rheological and friction conditions, slip on the San Miguel-Vallecitos fault should be favored due to better alignment with plate motion. Long-term faulting processes in the larger offset Agua Blanca fault may have lowered slip resistance, allowing accommodation of motion despite misalignment with plate motion.