| We present results of a new probabilistic seismic hazard assessment for
Puerto Rico and the U. S. Virgin Islands (PRVI). The study area is located
along the boundary between the northeastern Caribbean Sea and the Atlantic
Ocean, at the intersection of the Greater and Lesser
Antilles Island chains. These islands demarcate the boundary between the
North American and Caribbean tectonic plates, with the North American plate
moving west-southwestward relative to the Caribbean plate at a rate determined
from GPS geodesy of 19.4 mm/yr (Jansma and others, 2000). West of PRVI
the two plates move along typical transform structures (the east-west-striking,
left-lateral Oriente and Enriquillo – Plantain Garden faults, and
related structures). Southeast of PRVI the North American plate subducts
westward beneath the Caribbean plate, forming a typical volcanic island
arc (the north-south-trending Lesser Antilles). Plate interaction near
PRVI, in contrast, occurs in a 250-kilometer-wide, east-west-trending zone
of complex transpressional deformation, delimited by the Puerto Rico Trench
in the north and the Muertos Trough in the south. Puerto Rico and the Virgin
Islands lie on a shallow submarine bank within this complex deformational
zone. |
