Although there are always worries about how much money actually makes it to people affected by disasters, even if only part of it gets there it is a help.
When disasters hit poor countries, like Haiti, the world responds quickly and generously with donations. When industrialized nations are hit by massive disasters they frequently are not seen as being in need.
Giving is a good way to help remind yourself that if these people lived down the street from you and you could see and experience what they had to deal with, you would be moved to help them, regardless of their income level.