[JimSEA]

The geologic history of the Hawaiian Islands would suggest that numerous Tsunamis will originate in land subsidence there alone. The warning system cannot be the individual monitoring of each potential slide area throughout the oceans but rather should be space based and more generalized. To do this efficiently, problem areas on islands, sea-mounts and volcanically active areas need evaluating and mapping.

The incidence of such waves is frequent in geologic terms but rare in Human terms. :)

[Strategerist]

Bright side of things is that there's strong evidence that landslide tsunamis rapidly weaken with distance; they can be incredibly high close by, but lack the ability to propagage thousands of miles, one of the reasons most tsunami researchers think the whole ridiculously overhyped "Canary Island Volcano collapse would wipe out the East Coast" scenario is a crock.

You get a much more confused, complex system of waves from a landslide that dampen each other out over long distances.