Typhoon hayan hit the Philippines and many lives were lost.
Responce, that means getting ready for when the disaster actually happens and making sure everyone is safe.
Recover, when your at this stage that means you're well recovering from the disaster, you're also making sure that you are rebuilding all the important buildings like houses.
Reduce, when you reduce you make sure that all the damage that was caused is "reduced" also to make sure that no one gets hurt.
Readiness, when you are up to this stage that means that you have done all the other instructions on what to do in case of a emergency, well when it comes to readiness all it means is that you are ready for when the next emergency happens.