Relative motion between the Caribbean and North American Plates from GPS geodesy

Yellow triangles represent stations; red arrows represent motion of station with respect to stable North American craton and thin line ellipses are their error ellipses; yellow lines represent motion with respect to the Turks and Caicos station and thick line or yellow ellispses are the error ellipses. Arrow in top right corner is scale.

Diagram is from:

Dixon, T. H., F. Farina, C. DeMets, P. Jansma, P. Mann, E. Calais, 1998, Relative motion between the Caribbean and North American plates and related boundary zone deformation from a decade of GPS observations, Jounal of Geophysical Research, v. 103 (B7), p.15,157-15,182

Abstract. GPS measurements in 1986, 1994 and 1995 at sites in Dominican Republic, Puerto Rico, Cuba, and Grand Turk define the velocity of the Caribbean plate relative to North America. The data show eastward motion of the Caribbean plate at a rate of 21 ± 1 mm/yr (one standard error) in the vicinity of southern Dominican Republic, a factor of two higher than the NUVEL-1A plate motion model prediction, 11 ± 3 mm/yr. Independent measurements at sites on San Andres Island and St. Croix also suggest a rate that is higher than the NUVEL-1A model. Available data combined with simple elastic strain models give the following slip rate estimates for major left lateral faults in Hispaniola: 1. the North Hispaniola fault offshore the north coast of Hispaniola, 4±3 mm/yr; 2 the Septentrional fault in northern Dominican Republic, 8±3 mm/yr; 3. the Enriquillo fault in southern Dominican Republic and Haiti, 8±4mm/yr. The relatively high plate motion rate and fault slip rates suggested by our study, combined with evidence for strain accumulation and historical seismicity, implies that seismic risk in the region may be higher than previous estimates based on low plate rate/low fault slip rate models and the relatively low rate of seismicity over the last century.