Tital wave. (from Titan)
Spridle wave. (from the histrionic antics of Speed Racer’s brother)
Bridal wave. (from the tears at a wedding)
Homocidal wave.
Ecocidal wave.
Ripacidal wave. (from Latin for shore or bank)
Threwnami.
Slewnami.
Scruyunami.
Kangaroonami. (Australia only.)
But, my favorite, and the one I’d promote is… Spewnami.
Peace.
One thing I need to point out here is that in Japanese, “tsunami” means “seismic sea wave.” It doesn’t really mean “harbor wave.”
It is true that the Japanese compound word 津波 is composed of two characters that can be read as “harbor” and “wave”, but Japanese compounds generally are not taken as the sum of their individual meanings. The association between root meanings and compound meanings is much, much weaker in Japanese than in English.
Thus, there is no realistic tendency of confusing “tsunami” with something having to do with “harbor” in Japanese. But in English, IMO “tidal” and “wave” are fraught with individual meanings that can easily distract one from the understanding of the compound “tidal wave.”