Haiti’s now infamous fault line is a linear valley with a stream running through it, as shown in this false-color NASA topograph.
SeismoBlog reports the fault ruptured exactly underneath this valley over a length of approximately 25 miles.
Within roughly 15 seconds, the north shifted almost 9 feet to the left, while the southern block moved a similar distance to the right, resulting in a fault slip of about 18 feet.
Most Caribbean islands lie close to a major plate boundary.