The North America–Caribbean plate boundary west of the Motagua–Polochic fault system: a fault jog in Southeastern Mexico

We propose a model for the western end of the North American–Caribbean plate boundary. We suggest that, beyond the surface trace of the Motagua–Polochic fault system, interplate strain is distributed along the Reverse Faults Tectonic Province, a zone of long, narrow anticlines cut along their flanks by reverse faults that generally eliminate the intervening synclines, and the strike-slip faults of southeastern Mexico, a system of at least nine major faults with left-lateral displacement and documented seismic activity. The reverse faults act as a stepover (fault jog) between the strike-slip faults and the Motagua–Polochic system. Comparison with available stress data and models of the stress field at a stepover agree well with the observed pattern of folding and faulting in the area. Proposed displacement and seismicity along each individual fault in the SE Mexico strike-slip system must be small because interplate strain is shared between at least seven major strike-slip faults. We suggest that motion between North America and the Caribbean dies out at the northwestern end of the strike-slip faults.