Globally, the modelled mortality risk associated with floods and tropical cyclones was estimated to have peaked in the year 2000 before trending down. In East Asia and the Pacific, (World Bank regions) for example, the number of people exposed to floods and tropical cyclones each year is estimated to have increased by around 70% since 1980, while modelled mortality risk is estimated to have halved (UNISDR, 2011). However, in sub-Saharan Africa, estimates indicate that modelled flood mortality risk has grown consistently since 1980 (UNISDR, 2011) because increasing population exposure has not been accompanied by a commensurate reduction in vulnerability. Not all countries have been able to reduce the vulnerabilities associated with disaster mortality faster than the exposed population has increased.
Disaster mortality risk is closely correlated with income and the quality of governance. Since 1990, almost 90 per cent of the mortality recorded in internationally reported disasters has occurred in low and middle-income countries (see Figure).
Furthermore, despite some notable exceptions, early warning is rarely effective in the case of earthquakes. People do not die in earthquakes; they die in buildings that collapse or catch fire in earthquakes, and there is rarely time to evacuate to safe areas and shelters. Consequently, many of the improvements in disaster management which have been so effective in reducing disaster mortality from floods and storms have not been as effective in the case of earthquakes. Furthermore, while economic development may lead to declining weather-related mortality, it may actually bring about increases in earthquake mortality, as rapidly increasing exposure outpaces those reductions in vulnerability achieved through improved building and planning standards.
Since 1990, around 85 per cent of internationally reported earthquake mortality has occurred in low and middle-income countries. In these countries, the number of exposed buildings increases exponentially with rapid economic development and urban growth. However, the quality of urban governance, including the application of building codes and planning standards, is generally weaker than in high-income countries (UNISDR, 2009a).
Moreover, more than 45% of mortalities since 1990 is concentrated in four intensive events (Cyclone Gorky in Bangladesh in 1991, the Indian Ocean tsunamis in 2004, Cyclone Nargis in Myanmar in 2008 and the Haiti earthquake in 2010). While the mortalities from these events give the impression that mortality is on therise, this trend is not statistically significant and changes arbitrarily depending on the time period chosen and the specific intensive disasters occurring in that period.