New Kinematic Block Model for the Caribbean Plate

The quasi-frontal subduction of the north and south American plates under the Lesser Antilles and the left- and right-lateral strike slip along the northern and southern margins of the Caribbean plate offer the opportunity to study the transition from subduction to strike-slip faulting along major plate boundaries. In addition, the segmentation and degree of interplate coupling along the Lesser Antilles subduction is key to our understanding of the earthquake potential of a subduction zone whose length is similar to the rupture area of the Mw9.0, 2011, Tohoku earthquake in Japan. Previous studies used GPS data and a block modeling approach to infer coupling at the plate interface and strain partitioning at the transition with strike-slip fault in the northeastern Caribbean (Manaker et al., 2008; Benford et al., 2013), with three main findings: (1) a correlation between strong interplate coupling and strain partitioning, (2) low coupling of the Lesser Antilles and Puerto Rico subduction, and, (3) internal deformation within the upper plate in Hispaniola. These studies were however based on a sparse and inhomogeneous GPS data set. Here we use a much updated geodetic GPS data set (~300 stations, 50% continuous) and earthquake slip vectors to expand these previous studies to the entire Caribbean region (excluding Central America, except to define the stable Caribbean plate). We use the block modeling approach described in McCaffrey et al. (2002) to test the optimal block geometry for the northern, eastern and southern boundaries of the Caribbean plate. We solve for variations in interplate coupling along the subduction plate boundaries, estimate angular velocities for each block/plate, and determine strain accumulation rates for all major faults in the region.