Tsunami

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)

Other references
The Eleventh Doctor described a potential outbreak from the Dalek Asylum as a "tsunami of insane Daleks." (TV: Asylum of the Daleks)