A widespread scarcity of food. (no food available)
famine
An outbreak of a contractible disease that spreads through a human population
Epidemic or pandemic
A period of unusually and excessively hot weather
Heat wave
Too much rain in an area
flood
When soil on a mountain slope breaks off
landslide
The same as a landslide but in snow
avalanche
Often started by lightning or drought
Fire
When lava explodes out of the earth.
volcanic eruption
A period of no or very little rain.
Drought