[bd476]

Chode wrote: " question(that may already been asked/answered)

isn't it more a function of the degree of seafloor displacement that causes the wave and not shaking???"

The simple answer is that water has to be displaced, and/or shoreline eroded for there to be a tsunami.

A major quake on a bad shoreline has the potential of causing the shoreline to slough off enough material that it changes the slope of the shoreline, displaces water and greatly increases the risk of a local tsunami.

Seafloor shifting from a major quake on a seafloor fault has the potential to create a tsunami, depending upon the location of the fault, the type of slippage, how far the plates shifted, the magnitude of the quake, etc.

Here's a very simplified graphic showing a tsunami, Chode.

[Global2010]

Excellant example of what displaced water of a tsunami does.

Sure helped me grasp it even after all the education posted on tsunami events.

[Chode]

thx...