That sounds kind of obvious from a capital standpoint alone. Disasters cause expensive damages so anyone in a position to repair stands to make money. Anyone who lacks the reserves and needs loans and financing would be needed. I don't think it in itself qualifies as unethical even - while uncomfortable to make money from the misfortune of others the alternatives are worse.
Now other associated unethical practices may be involved like price gouging, and probably happened with certainty given both the breadth of history and human greed. It goes without saying that causing the bad situation and then benefiting is an ethical failure even without any bad intent. Deliberately causing it being clear evil.