Just days ago I made a similar comment to my husband. I'll be watching the thread to see if someone has an answer (if I don't find it online first). Great minds & all...right?!
The USGS indicates that the epicenter is 10 miles SW of Port Au Prince, which is under the island...not under the ocean. This may limit the chances of a tsunami.
Depends on how deep the fault is. Lots of displaced water.
Effects of an earthquake under shallow water. The great Christmas tsunami was so huge because the fault dropped a considerable distance. I think they said 60 feet, along a front dozens of miles long. A lot of water was displaced. As deep water waves move into shallow water, the top water moves faster than the bottom water and causes very high waves to build up.