The Federal Emergency Management System (FEMA) in the US recognizes 17 types of natural disasters. They are: Chemical emergencies, dam failures, earthquakes, wildfires, floods, hazardous material incidents, heat, hurricanes, landslides, nuclear power plant emergencies, terrorism, thunderstorms, tornados, tsunamis, volcano eruptions, and winter storms.
But there are also landslides, dust storms, invasive species, avalanches, droughts, tropical storms, ship and land transport accidents, and major aircraft accidents. There are pandemics and illness breakouts. Nuclear power plants are not the only source of radiation releases.
While terrorism, chemical emergencies, dam failures, hazardous material incidents, nuclear emergencies, and transportation accidents might appear to be easily severable from natural disasters, the reality might be that all of these could happen either as a consequence of a natural phenomena, or by using a natural phenomena to enhance terrorist activity, such as distributing a biohazard during certain weather conditions or in natural habitats.
An airline disaster, for example, is the reason that a volcano in iceland is currently causing an air travel shutdown throughout Europe. Years earlier, an airplane suffered complete engine failure because of the ash from an unseen volcanic eruption. Fortunately, good piloting saved the aircraft and passengers, but natural phenomena can be the cause of disasters in man made operations that would normally have functioned properly.
Invasive animal, aquatic, pathogen, insect and plant species constitute natural disasters that are natural in all aspects, except for their introduction. Human beings may use the latest technology to bring in living things that have no local predators to control their population, but the consequences are often disastrous and are realized through quite natural processes.
Disease pandemics, war and deadly pollution should be considered as natural disasters. Anything that greatly decimates human, plant, and animal populations creates natural conditions that can challenge the best efforts of chaos theorists. Whether from terrorism, natural pandemic, or as a strategy of war, killing off of much of the living population will even drastically change the atmosphere by the venting of gases when living things decompose.
Bad land management is one of the greatest natural disasters, even if the beginnings or causes are by humans. Desertification from ruined soil structures, deforestation, overfishing and pollution of the aquatic biomes, brackish water biome destruction, water diversions, riparian damage, and other issues of land management and preservation are important because of the natural disasters that result, including dust storms, landslides, and sterile ocean environments.
In summary, even if the actions are in remote areas of the world or are caused by man, the effects and resolutions are more often than not, natural disasters.