Mars is a harsh environment and human life is only made possible due to incredibly durable structures - designed specifically to resist it. Every now and the however, extremes will appear that will test the resilience of the colony on a much higher level. Sensor Towers and RC Seekers extend any advanced warnings for disasters.
Disasters range in likelihood depending on the colony coordinates. They can also be eliminated completely via the No Disasters Game Rule or increased to maximum all across Mars by their respective Game Rules. Alternatively their effects can be lessened by the Easy Maintenance Rule.
Disasters lower the Sanity of all Colonists, particularly if their Dome does not have a Security Station.
In Green Planet terraforming can slowly reduce and eventually eliminate the Martian disasters but also create new ones.