Disaster is a game effect introduced in the Cities in Ruin that is used when Shudde M'ell is the Ancient One, or when a Prelude that allows for Disasters is used.

Whenever Doom advances to a position on the Doom Track with an Eldritch Token on it, the investigators draw one random Disaster, resolve its effects, then discard the Eldritch Token on the track. Some Disasters will cause Devastation to occur on a space, and some will not. If all nine major cities are devastated, the players immediately lose the game.  

Several of the Preludes that come with the Cities in Ruin expansion can allow for a Disaster to trigger when certain events in the game are played.

Title City Devastated
Unnatural Occurrences Leave Rome in Shambles! Rome
Tsunami Destroys Tokyo! Tokyo
Terrifying Creatures Overwhelm Arkham! Arkham
Sydney Burned To The Ground! Sydney
Shanghai Flooded! Shanghai
Meteors Fall On Istanbul! Istanbul
Hurricane Strikes Buenos Aires! Buenos Aires
Explosions in London! London
Earthquake Hits San Francisco! San Francisco
Waterspouts N/A
Upheaval N/A
Polar Vortex N/A
Otherworldly Rifts N/A
Meteor Showers N/A
Frozen Rails N/A
Destructive Cyclone N/A