Well, that’s hard to explain - I think the best answer I’ve heard/seen for that came from John Polkinghorne in Questions of Truth. Polkinghorne is a former physicist turned priest. And he approaches it from a scientific standpoint - there seems to be a need for a certain amount of “openness” in the system in order for life to arise. And that means that the system has to be open to the possibility of chaos. Thinking in human terms, God gives us freedom in order that we might love - because this is our purpose. But love is not love without freedom. And so for freedom to exist, there is always the possibility that we might abuse it.
Now as far as disasters go - the system of the universe is so complex and beyond our ability to reason still - but, it does seem that a lot of the “natural” disasters we’ve been having lately have actually been our own damn fault. Did you hear that deforestation is likely the cause of the recent mudslide in Washington State?