So as for the one who tries to ascribe these matters to the nature, and he calls them 'natural disasters'...if he intends by this that the nature itself is that which is causing these matters, then he is a Kaafir, a disbeliever.
In a hadeeth Qudsi, the Prophet (sallaahu 'alayhi wa salaam) said: He (Allaah) said: "This morning one of my slaves became a believer in Me and one a disbeliever. As for him who said: 'We have been given rain by virtue of Allaah and His mercy,' that one is a believer in Me, a disbeliever in the stars; and as for him who said: 'We have been given rain by such-and-such a star,' that one is a disbeliever in Me, a believer in the stars.'"
So Allaah has clarified here that the one who ascribes these matters - whether it be rain, lightening, thunder, the Tsunami, whatever it may be - if he attributes that to the creation, then he has disbelieved in Allaah.
If a person says, for example, in describing an earthquake that the earth begins to do this and they begin to explain the actual way that the thing takes place, then this is a scientific explanation, but we understand that it is Allaah Who caused all of that to take place. That it is all from the Might of Allaah. So he does no ascribe that matter to the nature itself.
Subhanak Allaahuma wa bihamdika ash-hadu anlaa illaaha illa anta astaghfiruka wa atubu ilayk
If I said anything correct, then it is from Allaah (subhanahu wa taa'ala), and if I erred, then that is from me and shaytan.