Mass disasters can be parsed into two basic types:
(1) Man-made, which in turn can be divided into those that are
(a) Accidental with unintended consequences, and
Examples The 1984 ecodisaster in Bhopal India in which a thermogenic reaction vaporized 42 tons of methyl isothiocyanate that covered an area of 80 square km and killed up to 10,000 people; the 1989 Hillsborough disaster in which 96 Liverpool league football fans died from crush injuries and suffocation; the 2003 Station nightclub fire in which 100 died due to illegal indoor use of outdoor fireworks (this fireworks idiocy have since caused nightclub fires in Argentina, Brazil, China, Russia, Romania, and Thailand)
(b) Intentional or collateral consequences of official policies
Here, the mass disaster occurs in a background of one or more of the following components: oppressive or extremist regimes; use of weapons prohibited by international conventions, targeting of healthcare workers and/or hindrance of rescue efforts, torture of victims, forbidding of unbiased media coverage; wide disparity between official and unofficial death tolls. Examples Syria’s use of chemical weapons on its own citizens (death toll unknown); Tiananmen Square Massacre (218 civilians–official figure; up to 2,600 civilians–estimates including now retracted Chinese Red Cross statement).
(2) Natural disasters or, if you will, acts of God, which also come in two flavours:
(a) Geological disasters. These tend to get a population’s immediate and undivided attention.
Geological disasters are caused by shifts in tectonic plates with direct consequences in the form of earthquakes, and indirect consequences in the form of volcanoes and tsunamis. Per the US Geological Survey, the Earth hosts one quake per year measuring above 8.0 on the Richter scale, 17 above 7.0 and gazillions of hiccups below 4. The most violent earthquake on record was the 1960 Valdivia (Chile), which measured 9.6 on the Richter; the most expensive was the 2011 Tohoku quake and tsunami ($235 billion); and the greatest number of lives lost was in the 1556 Shaanxi quake that killed 830,000.
(2) Meteorological phenomena As inhabitants of many islands in the Caribbean can testify, tropical storms (hurricanes) with Category 4 and 5 winds flatten most structures in their path and the accompanying floods and surges will finish them off. Anno Domini 2017 was the worst year on record with estimates for the price of rebuilding in the aftermath of Hurricanes Harvey, Irma and Maria as high as $300 billion, beating the unenviable record for the highest cost natural disaster set by the Tohoku earthquake and tsunami set in 2011.
Disaster medicine is the field that coordinates and provides the medical response to mass disasters follows a so-called disaster life cycle of preparation, planning, response and recovery while providing health care to survivors.