Hi Glen,

Speaking, as always, as an interested amateur, I would certainly think that there is no reason a normal-faulting quake of the same size as the Solomon M8.0 quake would not be just as tsunamigenic. Problem is, normal faulting almost never produces quakes of that size. And, when they do occur, they are generally not under the ocean. If they are that size, they are not part of the normal-faulting mid-ocean ridge system - they are likely to be the sort of failed-rift type, mid-continental sort of thing exemplified by the New Madrid quakes. A quick search seems to indicate that the largest normal-faulting quake in the last 20 years was the 1983 Borah Peak M7.3 quake (in Idaho).

Michael F. Williams
Arroyo Grande, CA USA