First off I wouldn't say landslide because if it was a landslide in more than likely would have cracked the concrete on the floor that the people are standing on and there would be more of a mess than what is show in the picture. Next I wouldn't say tsunami depending on how frequent this disaster was, if it was a tsunami more than likely most of that rubbish would have been soaked with water in other things that were in the water as well and I wouldn't say flood either because once again nothing is soaked with water with in that picture not even the concrete that the people are standing on so I say that the most reasonable answer would be earthquake due to them being know for destroying buildings alot.