"There is no disaster that befalls the earth or your own selves but is inscribed in a book before we make it happen". Al Hadid 22

Are these natural disasters or are these consequences of our actions? How do we reconcile this with the concept of free will?

It can be any calamity that befalls a person, and just because we have free will to decide, doesn’t mean that Allah in His infinite knowledge doesn’t already know about it. He knows every choice we are going to make, even before we make it.