[Windflier]

Think about the kind of tsunami it would generate if it happened under water in the Atlantic, I think there is a undersea mountain like that out there somewhere.

I think that's the Azores. There's a mountain there that has a huge fault running through it that runs parallel to the eastern seaboard of the US.

Geologists who've studied it, say that if it ever slips, that mountainside will go into the Atlantic, which will send a tsunami to our east coast.

[Paul R.]

You may be referring to La Palma. Good, non-hyped article here:

https://noc.ac.uk/news/could-flank-collapse-la-palma-cause-tsunami

Note the MUCH larger volume of material involved: 350 cu. kilometers (La Palma) is roughly 4 orders of magnitude greater, if I did the math right...(!)