Would you kindly not tell me what specifically to worry about, DoomInTheUK, because if you do, then i am forced to reserve the right to respond in kind, with something like "worry about something else than this topic". It won't end well, so let's not start with it. Deal?
To the subject. I know what you mean, but i used the "tsunami" word for simplicity. Thing is, when "just a big wave" gets big enough, its effects can and will approximate those of "proper" tsunami wave rather well.
Next, i certainly didn't mean underwater part of ice being responsible for forming up the wave. Therefore your argument about it, while true in itself, - is irrelevant to what i was talking about. For the record, "cascade failure" i meant was all about above-water parts of WAIS (in the future, after WAIS loses most/all shelves and will be melting in its core parts).
One can see both such "cascade failure" (only partial and limited, though) and also resulting water wave of many meters height - in about 1 minute
.
Note that the above video evidence is produced by calving of mere thousands of tons (from the looks of it) of ice which drops down to sea level from mere several dozens meters height (from the looks of it). Imagine what will happen if we'll have trillions tons of ice dropping down to sea level from many hundreds / couple thousands meters elevation. The mere mass and inertia of the fall could easily move whole water column as you "request", even produce a crater in the seafloor if it's shallow enough waters under the collapsing part of the WAIS (and there are plenty of locations).
At more deep water locations, it might not move the _whole_ water column, but it'd still be a wave of unprecedented proportions if large enough portion of WAIS fails structurally and drops down, crashing through all the openings and "caves" created by underside melt, as described above.
And if anyone doubts whether trillion-ton scale fracturing is possible, - quite "conviniently", an iceberg more than 1 trillion ton in mass separated from Larcen C just today, i heard elsewhere; this is probably already reported in some nearby topics. So you see, even floating parts can fracture at this scale - means, to me, that parts which are "anchored" and have much of their ice weight being supported by solid ice structure and ultimately bedrock, - those parts will possibly fracture at even much bigger scale "momentarily", as soon as underside melt corrodes supporting solid ice structure sufficiently.
It might end up being thousands of trillions tons of ice dropping down at some point in a single event. The sort of wave created out of such event may not have appropriate term in english yet - it's not exactly "tsunami" and it's too big to just be referred as "just a big wave locally" (like the one in the video linked above), but do we really need to stay blind to this future danger only because we don't yet have common established term for such events?
I think we don't.
