birdie, as a parent you have, within reason, to let your children do things that are risky because it's one of the ways they learn and become independent. You may know that when they fall off the chair they are jumping up and down on they'll get hurt. But it's better for them to find out for themselves by falling off the chair than by falling off the top of a building.
We live on a world where disasters, natural and man made, happen. We can do our best to prevent the man made ones, and deal with the natural ones as best we can. For the faithful such disasters are a test, as are the normal everyday troubles we all have.
God has laid down a set of rules for living well - follow them and you will get to heaven, don't follow them and you'll be sorry. So when you are faced with a disaster of some kind, it's how you behave that matters. The test in is whether you stick with God's rules or not, even when not doing so will make things a lot easier for you.
Even your own questions about how an all knowing God could have let this happen become a test of faith, in the sense that the answer is "I don't know, but I believe anyway". so, congratulations ! Even in your unbelief you are, for the faithful, doing some of God's work in the world !