David Stevens commented on the Good Word cataclysm by noting that calamity is in with those [words = catastrophe, cataclysm] also, but probably connotes less than a catastrophe.”
He is right. My response is that I am always amazed at the subtle differences in words of the same semantic category available to careful speakers. In this case we can find a long continuum of words that indicate increasing intensity of problems: problem < trouble < calamity < catastrophe < disaster < cataclysm.
There may be other words that we could insert in this continuum but we find such continua in words expressing almost every category of variable concepts.