It’s going to happen, so where’s your umbrella?
Crisis — It only exists because you aren’t prepared.
That’s the difference between one of those and a tragedy. There is absolutely nothing you can do about nature going bananas, colossal malfunctions or the dregs of society out on parade. Those things will inevitably happen when you least expect it. However, your ability to be prepared for the inevitable — or inability thereof — is what makes it a crisis.