Historical perspective

From 1990 to 2013, natural disasters affected approximately 4.8 billion people worldwide. They caused about 1.6 million deaths and 5.3 million injuries and left over 109 million people homeless. During this period, while geophysical disasters were responsible for 52% of total mortality, water- and weather-related disasters accounted for 97% of the people who were in need of immediate assistance; that is, the affected population ( Fig. 93-1 ). Moreover, adverse impacts of climate change are predicted to increase the risks of hydrometerological disasters by increasing the intensity of hurricanes and cycles of droughts and floods.

Number of People Killed and Affected Due to Natural Disasters, 1990-2013.

(Data source: EM-DAT: The OFDA/CRED International Disaster Database . Brussels [Belgium]: Université Catholique de Louvain. Available at: http://www.emdat.be .)

Natural disasters are a part of the human experience, and as the size of the human population increases, it can be predicted that the impact of natural disasters on society will grow, for the following four reasons :

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  Disasters are continuing to increase in frequency and/or intensity

  
  
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  Disasters are affecting more population centers in the world community

  
  
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  The economic costs associated with disasters are increasing at an alarming rate

  
  
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  More people are moving to areas subject to natural hazards such as cyclone- and tsunami-prone coastlines, flood-prone river basins, and earthquake-prone cities

The risks associated with disasters can be intensive or extensive. Intensive risk refers to the risk of high-severity, mid- to low-frequency disasters, mainly associated with major hazards. Examples include the 2010 Haiti earthquake, the 2011 Japan earthquake and tsunami, Hurricane Katrina in 2005, and Hurricane Sandy in 2012. Extensive risk is used to describe the risk of low-severity, high-frequency disasters, mainly but not exclusively associated with highly localized hazards. While these events have significant cumulative impacts on the societies and health of populations, unfortunately most often they do not receive enough attention by media and community planners. The loss and damage associated with extensive risks are increasing because of poor urbanization, environmental degradation, poverty, inequality, and weak governance. According to the 2009 Global Assessment Report on Disaster Reduction , extensive risk events were responsible for about 65% of damages to hospitals. A study on the impacts of natural disasters on primary health centers revealed that extensive risk hazards were responsible for moderate to severe damages in about 26%, 28%, and 59% of structural damages, nonstructural damages, and functional failure, respectively.

Current practice

Natural disasters obtain their names from the hazards that trigger them. Accordingly, natural hazards can be characterized by their magnitude or intensity, speed of onset (rapid or slow), duration, and area of extent. The Center for Research on the Epidemiology of Disasters (CRED) provides a classification for natural disasters based on the hazard’s origin as follows :

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  Geophysical disasters are those originating from solid earth events such as earthquakes, tsunamis, and mass movements (dry).

  
  
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  Hydrological disasters are events caused by deviations in the normal water cycle and/or overflow of water caused by wind. This category includes floods (river flood, flash flood, and storm surge or coastal flood) and mass movements (wet).

  
  
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  Meteorological disasters are due to short-lived, small- to medium-scale atmospheric processes, that is, from minutes to days. Meteorological disasters include tropical storms, thunderstorms/lightning, snowstorms/blizzards, sand/dust storms, and tornados.

  
  
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  Climatological disasters are those caused by long-lived, medium- to large-scale processes that range from intraseasonal to multi-decade events. This category includes the following hazards: extreme temperature (heat waves and cold waves including frost), extreme winter conditions (snow pressure, icing, freezing, rain debris, and avalanche), drought, and wildfires (forest and land fires).

  
  
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  Biological disasters are due to the exposure of living organisms to germs and toxic substances. Examples are bacterial or viral epidemics, insect infestations and animal stampedes.

As expected, there are variations in terminology. For instance, the term hydroclimatological hazards includes both water- and weather-related hazards. The United Nations International Strategy for Disaster Reduction (UNISDR) defines a hydrometeorological hazard as a process or phenomenon of atmospheric, hydrological, or oceanographic nature. Moreover, biological disasters such as epidemics most often are not included in natural disaster reports.

In some cases, one hazard may result in another, as the case of a tsunami created by an earthquake, a flood caused by a hurricane, or a landslide following an earthquake or a hydrological event. Rockfall, landslides, avalanches, and subsidence can be classified both as geophysical and hydrological hazards depending on the original physical forces. The term socio-natural hazard refers to human activities that increase the probability and/or intensity of a natural hazard. Examples include increased flood occurrence following deforestation and increased intensity of cyclones following global warming induced by emission of greenhouse gases. Natural disasters can also trigger the occurrence of technological disasters. The 2011 Japan earthquake and tsunami damaged the power and cooling systems of nuclear power plants and caused an International Nuclear Event Scale (INES) Level 7 accident. About 20% of nuclear reactors worldwide are operating in high seismic zones.

Natural disasters are among the most serious global challenges. The international community has taken initiatives to reduce risk of disasters at the country and local levels and those that cross state boundaries. The second Wednesday of October has been designated as the International Day for Natural Disaster Reduction. The Yokohama Strategy for a Safer World, adopted in 1994, was among the first consolidated international initiatives aimed toward disaster risk reduction. The lessons learned from implementation of the Yokohama Strategy led to development of the Hyogo Framework for Action (HFA) during the World Conference on Disaster Reduction was held in January 2005 in Kobe, Hyogo, Japan. The HFA is an agreed upon international framework for the period of 2005 to 2015. Since 2005, many countries have made some progress in terms of enhancement of capacities in early warning, disaster preparedness, and response that accordingly has contributed to a decreasing trend in mortality risk. Despite these advances, the risk of disasters is still high, causing people to suffer from the associated economic loss and damages, both in developed and less developed nations.

To follow up with the HFA, based on a conference that was held in March 2015 in Sendai, Japan, the United Nations developed the Sendai Framework for Disaster Risk Reduction for the 2015–2030 period. This new framework aims to achieve the following outcome: “the substantial reduction of disaster risk and losses in lives, livelihoods, and health and in the economic, physical, social, cultural, and environmental assets of persons, businesses, communities, and countries.” According to the framework, to attain this outcome, the following goal must be pursued: “Prevent new and reduce existing disaster risk through the implementation of integrated and inclusive economic, structural, legal, social, health, cultural, educational, environmental, technological, political, and institutional measures that prevent and reduce hazard exposure and vulnerability to disaster, increase preparedness for response and recovery, and thus strengthen resilience.” Because of a proactive contribution by health experts in development of the Sendai Framework, led by the World Health Organization, the health-related subjects have been well highlighted in this global initiative.

Management of natural disasters follows the same tenets of the disaster management cycle described in Chapter 1 of this textbook. The four phases of this cycle include prevention/mitigation, preparedness, response, and recovery.