Natural warning signs of tsunamis: Human sensory experience and response to the 2004 great Sumatra earthquake and tsunami in Thailand

Natural warning signs of tsunamis include ground shaking from earthquakes and unusual sea-level fluctuations, wave forms, and sounds. These signs can alert people to impending tsunamis, but no research has explored the recognizability of these signs or the social-cognitive factors that affect human behavioral response to them. Of 663 interviewees, 24% felt ground shaking during the earthquake; 69% saw something unusual about the ocean before the first wave reached land, mostly a receded shoreline; and 55% heard something unusual. Despite these levels of observation, most people did not evacuate. In fact, 65% saw other people in the danger zone at the time of the tsunami impact. Most respondents had to run for their lives but could not identify a safe place. There are major differences in experience among north, central, and southern coastal Thailand, reflecting social, topographical, and hydrological factors. © 2006, Earthquake Engineering Research Institute.