An earthquake's epicentre is the point on the Earth's surface directly above the point deep in the crust where the movement occurred. To say that the epicentre was directly beneath Port au Prince is inaccurate on two counts, firstly in that the epicentre is not underground and secondly in that, in this case, the epicentre was actually several miles to the west of that city. That puts it even further away from the populous areas of the Dominican Republic, which is to the east of Haiti, and which did feel the shock but which was spared major damage. It was simply too far from the epicentre.