Zombies. Though fictional, many emergency management departments have included 'Zombie Preparedness' campaigns into their social media methods to help raise awareness for the need to prepare for disasters.
Zombie apocalypse
An ice storm can be a natural disaster.
zombie apocalypse
A natural disaster that starts with "H" is -Hurricane & -Heat Wave
Tornado
not that I know of. sorry. :(
droughts disease
cyclone
landslide
· Zeppelin airship Hindenburg disaster in 1937.
monsoon flood, mudslide
Yasi
Yes: forest fire, flood.