This is "Pay Attention To Me NOW!" crap. See:
http://www.drgeorgepc.com/TsunamiMegaEvaluation.html
by a professor in Hawaii who took this scare story apart. He agreed with an estimate of a worst-case scenario of about a one-meter high wave at the U.S. & Brazilian coast.
"Full Navier-Stokes modeling brings the maximum expected tsunami wave amplitude off the U.S. east coast to about one meter. Even with shoaling effects, a tsunami from a La Palma slide would still be of concern but does not present an unmanageable threat or a significant far field hazard."
Heck, I've seen storm generated surf that dwarfs the recalc of a few meters. Even the worst case for the E.Coast at 20m is, as many surfers know, is not unheard of in a number of areas. Although it would cause plenty of damage in areas that do not routinely get big waves.