[Strategerist]

Poking around the web earlier today I ran across an article on the 1964 tsunami....apparently they carefully examined the sea floor recently and to their immense surprise didn't find an underwater landslide. That whole tsunami seems to be somewhat of a mystery.

Regarding the mainshock tonight a lot about it seems strange. It may take months to sort out what happened and exactly how big it was.

What I don't get is ALL of the large aftershocks being NORTH of the epicenter of the mainshock.

[capitan_refugio]

As I recall, there was a massive area of the seafloor that dropped several feet suring the earthquake. That could easily set up a low amplitude, long wavelength, wave-train that would result in tsunamis as they approached the coasts. (Tsunamis are not observed in the open ocean as high amplitude waves.)

I think you are correct about the lack of underwater landslides in 1964 - at least on a large scale.