Uh, I don’t know about that scenario.
Here in the northwest along the coast the subduction earthquake is out at sea where the marine plate is forced under the edge of the continental plate.
The coastline has been known historically (drowned forests along the coast) to cause the coastal areas to subside as much as 16 feet.
I'm no geologist, far from it..but the overwhelming majority of earthquakes of 7.0 or greater magnitude occur where the tectonic plates meet...IOW, where the earth is already cracked. Also, they're finding that most quakes NOT near a plate boundary are on fault lines that they didn't know existed before...and fault lines are just really smaller cracks.