Disasters which count
Pandemic
Ai mishap
Terrorism
Famine
Disease
Nuclear strike or accident
Infrastructure collapse
War also counts
Etc
Deaths from old age, traffic, etc don't count unless related (many people die crashing cars due to seeing a Kaiju for example). Note: things that have always been that way probably won't count as a disaster. Eg if someone credibly finds a way to logically reclassify a certain cancer as a type of environmental disaster, it still probably wouldn't count if that had been happening all along. So: non-uniqueness in time weakens the claim to be a disaster.
A death by disaster is an unintended (by the victim, at a prior state in time) death. Eg being converted to a cult which causes suicide can still be a disaster.
Since disasters have different time scales (instant vs gradual), it can be hard to quantify. This is how I'd like to do it here: at any starting point in time consider all residents of anxiety or region. If within a year at least 1% are dead from a disaster then YES.
So you can start at any point in time and that is the group of people who count.
So if the people later flee they individually still count. If later refugees come to the city after the time we are checking, they wouldn't count for this interval.