Most religions include the idea that everything that happens on earth is planned out by god. If such a god exists, then it is certainly part of his plan for people to die in disasters. If this is not true, there is simply no god. How can a god allow people to die in disasters if he doesn't want them to?
It is not God's will for people to die in major disasters. The disaster that strike and kill people are able to proved on how they occurred by science. God has no involvement in these disasters, so it is not possible that it is His will for people to die in them.
Disasters happen due to natural reasons unfortunately people are no exceptions to who gets kill. The fact of the matter is if an earth quake hits an area there are going to be people on the bad end of the line and there are going to be human lives lost no matter how you role the dice.