The phrase "immense disaster" is correct and usable in written English.
It can be used to describe a situation or event that has caused significant destruction or suffering.
Example: "The earthquake resulted in an immense disaster, leaving thousands homeless and in need of assistance."
Alternatives: "major catastrophe" or "huge calamity".
The images of Nepal last week have shown a desperately poor nation, overwhelmed by an immense disaster.
Despite hints of economic progress, we're still in the midst of an immense disaster, in which unemployment and underemployment are devastating millions of American lives.
"I think in the beginning we felt that if the international community could respond the way it did and that peace could come out of this immense disaster, then such spirit would make building a road a snap.
Two years later he announced the release of OT3, the "Wall of Fire", revealing the secrets of an immense disaster that had occurred "on this planet, and on the other seventy-five planets which form this Confederacy, seventy-five million yeago ago".
It describes the fall-out of an immense natural disaster that leaves few human survivors and a herd of genetically-spliced animals roaming in the atrophied wilderness.
Russia is on the brink of an immense human disaster, and President Yeltsin's days in office are numbered.
I've just painted a portrait of immense human disaster.
It is one of the worst such disasters to occur off the Italian coast in recent years; Prime Minister Enrico Letta tweeted that it was "an immense tragedy".
Though less well known in the West than two other immense political disasters visited upon the Chinese people by Mao Zedong, the Cultural Revolution and the Great Leap Forward, the so-called Anti-Rightist Movement to which the subjects of Mr. Yang's stories fell victim remains difficult to research because of continuing censorship.
Witness the immense popularity of disaster movies and thrillers.
