Does anybody know if a large object travelling at high speed impacting water would be detectable to the seismologists who monitor earth tremors and 'quakes?
I doubt it but when the WTC collapsed the shock was detected about 300 miles away. Some info on that here..
Seismic Detection
The aircraft impacts registered local magnitude (ML) 0.9 and 0.7, indicating minimal earth shaking as a result. The subsequent collapse of the towers, on the contrary, registered magnitudes of 2.1 and 2.3