This is a classic 'marching' earthquake along a strike-slip fault. History has them marching all the way to Jamaica. As well, the upper fault gets activated.
The only place to build a town is on deep sediment basins. That's why the effects are so strong.
ps. This is a thrusting strike-slip. That's why there is that long ridge, being the hanging wall.
pps. almost 2 cm/s in Jamaica, 1 cm/s in Dom. rep. probably on rock.