Nature, ie either
1. Natural, geophysical–eg earthquakes, volcanoes or weather-related–eg floods, hurricanes.
2. Man-made–transportation-related, structural collapse, war, hazardous materials, explosions, fires
Location Single site–eg explosion or multiple sites–eg hurricanes
Predictability Regular–eg hurricane season or sporadic–eg toxic spill
Onset Gradual–eg armed conflict or abrupt–eg accident
Duration Brief–eg natural disaster or extended–eg armed conflict
Frequency Often–eg flood, or rare–eg fire
.