I will say this though, it seems the rate of decline of ground motion doesn’t seem to be dampened by distance down there, to the degree it is up here.
Another-words, at 100 miles there’s still a large magnitude shake.
Up here at 100 miles the quakes can been quite minimal.
We would have similar shock transmissions distances. We simply haven’t experienced a 7.2 recently...
In other words...
In the western usa where we get most of our quakes that is the case due to the shallow bedrock (mountains). However, the Great Madrid shake near the Mississippi in Missouri knocked some brick chimneys down in Boston in the late 1800’s!
When that one goes again it will be bad for us, as not a lot of our infrastructure in the midwest or east was designed for large quakes. I think they have done a lot of work on upgraded bridges across the Mississippi - but oil and gas pipelines that supply the east will be hard hit.