baneful, black, calamitous, cataclysmal, catastrophic, consuming, consumptive, convulsive, deadly, demolishing, demolitionary, depredatory, desolating, destroying, destructive, devastating, dire, disastrous, doomful, fatal, fateful, fratricidal, grievous, herky-jerky, insurrectionary, internecine, jerky, nihilist, nihilistic, orgasmic, paroxysmal, radical, ravaging, revolutional, revolutionary, revulsionary, revulsive, ruining, ruinous, seismic, self-destructive, spasmodic, spastic, subversionary, subversive, suicidal, sweeping, tragic, transilient, upheaving, vandalic, vandalish, vandalistic, wasteful, wasting, withering, wreckful

For further exploring for "cataclysmic" in Webster Dictionary Online