This one is easy.

Why does a merciful God allow human-caused and natural disasters to happen.

Answer: I don't know.

I doubt whether there's ever been a natural disaster in which it's not been natural for thoughtful believers to ponder the question, and there are libraries full of answers, none of them informed, because humans do not know the mind of God.

Their answers cancel each other out, or are based on contrived reasoning of intellectual sleight-of-hand.

This does not mean that there's no value in discussing the theme: it helps us sort out other aspects of our experience of and witness to God.

Whatever else believers in the Bible find in the book, it all stops back with the observation that "he makes his rain to fall and his son to shine on the just and on the unjust."

Where biblical authors do address the issue, it can get pretty scary, as it does in Isaiah 45:7, Yahweh speaking: "I form light and create darkness, I make weal and create woe." And in the Book of Job we get three chapters of "who do you think you are?" questions when we want final solutions to our existential problems.

When good things happen, the believer is licensed to give thanks, but claiming to know why a hurricane cloud blew where it did or our team or army won--that's tricky, because then "when bad things happen" one cannot skip out and say that someone can know the "why."

Not having the answers in the ultimate sense has not deterred (us) believers from expressing belief. They, we, have instead to be more humble about what we claim--and do what we can to prevent man-made disasters.