Funnily enough floods (GCP) and fires (OVH) are two of the 3 things AWS explicitly mentions in the Well Architected docs. For a lot of companies an AZ going down is an annoyance or bad day but a whole region going down could be a real continuity risk.

> Each Availability Zone is separated by a meaningful physical distance from other zones to avoid correlated failure scenarios due to environmental hazards like fires, floods, and tornadoes.

https://docs.aws.amazon.com/wellarchitected/latest/reliabili...