*yawn*. A foot and a half isn't going to be all *that* bad
Sorry to continue off topic: Try to imagine ... a temporary very high tide, rather than a cresting wave. In addition to the "height", it's the wave-length you have to take into account. Tsunami's rarely become towering breaking waves. [That said, tsunamis can form into a bore - a step-like wave with a steep breaking front. Likely if the tsunami moves from deep water into a shallow river / bay] 1 1/2 foot on top of an existing high tide, could easily cause further flooding in the wrong locations (although as mentioned, not to the levels already experienced).
travels in general at approx 970 kph (600 mph)
True in the deepest parts of open ocean - upon reaching the shore-line it'll be travelling a lot slower. </off-topic> // Gav