The document discusses how tsunamis become disasters due to human involvement. It argues that without humans present, tsunamis would only modify uninhabited areas naturally, but not cause disasters. Tsunamis become disasters when they threaten human lives, destroy homes and livelihoods. Recent tsunamis like the 2004 Indian Ocean tsunami and 2011 Tohoku tsunami are used as examples to show how they caused widespread death, infrastructure damage, and environmental impacts like debris and nuclear accidents.