A tsunami or tidal wave was a devastating phenomenon. The Committee caused one by manipulating God, Norton Folgate and Yvonne Hartman. (AUDIO: Eye of the Storm) It caused a crisis in Cardiff, which was unprepared. (AUDIO: A Mother's Son)
As Gallifrey was translated into a pocket universe at the end of the Last Great Time War, the shock created a tsunami that threatened a town with the Third Doctor stopping it. (PROSE: The Day of the Doctor)
Other references[]
The Eleventh Doctor described a potential outbreak from the Dalek Asylum as a "tsunami of insane Daleks." (TV: Asylum of the Daleks)