Tsunami hazard and risk

Tsunamis have been given enhanced attention since the Sumatran earthquake of 26 December 2004, one of the greatest disasters of recent decades, with a death toll of at least 230000. This event was triggered by the largest global earthquake for 40 years (magnitude 9.2) and highlighted the impact of extreme natural events. Tsunami waves hit 12 countries bordering the Indian Ocean region (Figures 10.1 and 10.2), and tourists and nationals from many more countries were affected; for example, it is considered the greatest natural disaster in Sweden’s history due to the large number of Swedish tourists killed (estimated total of 543 fatalities -Kivikuru and Nord, 2009). Between 1900 and 1990 the NGDC Global Tsunami Database reports a total of 33500 fatalities due to tsunamis (NOAA-GDC, 2010), while in the period 1990 to 2004 there were in excess of 230000 deaths, largely related to this single event. As a consequence, tsunami hazard has been elevated towards the top of the natural hazards agenda. The tsunami that affected American Samoa in September 2009, the Chilean earthquake tsunami of February 2010 (Figure 10.3) and the Indonesian tsunami of October 2010 that resulted in over 400 deaths have re-emphasised the importance of tsunami hazard to coastal communities. The unanticipated scale of the tsunami impact on the Fukushima nuclear power plant in March 2011 further highlighted the need to advance the science of risk assessment for safety-critical facilities, and to develop more robust frameworks for assessing uncertainty (see Chapters 2 and 3).