During the Seacarib Cruise the region south of the Greater Antilles (Hispaniola and Puerto Rico) has been investigated. During this survey we recorded continuously Seabeam, magnetic, gravity and seismic digitized data. The Muertos Trough disappears toward the west where the Beata Ridge reaches the trough. The volcanic rocks outcropping in the Southern Peninsula of Haiti and those of Beata Ridge have the same composition. These oceanic rocks and the emergence of the Muertos prism suggest a collision between Beata Ridge indenter and the northern block of Hispaniola. The Caribbean Plate has an eastward motion relative to the America Plate; however the crushing of the northern Hispaniola Block between two jaws, Beata Ridge and Bahamas Bank, leads to the northeastward tectonic escape of the Puerto Rico Block.