Post-traumatic stress disorder (PTSD) is a delayed onset and persistence of psychiatric disorders that result from an individual experiencing, witnessing, or encountering one or more actual deaths, threats of death, serious injuries, or threats to somatic integrity involving self or others. From the definition of PTSD, we can infer that natural disasters such as earthquakes and mudslides, which are both sudden, threatening and catastrophic, may be more likely to cause PTSD symptoms in the affected population. So how to check to know you have a disaster reaction? 1. Very depressed. 2. Causing problems in your life. 3. Lasts for more than 2 or 3 months. These symptoms may mean that you have PTSD.