How do natural disasters affect the world?
By two effects: Direct ones and Indirect ones.
When there is a natural disaster in a part of this planet, some people die, some economic losses ocur there, some people loose their houses,jobs, etc. This is a direct effect (as I call it).
If the disaster is serious enough to kill thousands (such as Hurricane Katrina) emergency aid is sent from different countries. Search efforts can last weeks. Therefore, if there is another disaster happen in another part of the planet, the search efforts there would not be enough (I call this as indirect effects). Some economic losses due to loss of jobs of people in long term are considered as indirect effects.