My question is how exactly does the game determine when these events occur? I have read that they occur "randomly" but I would like more detail, if that is known. Once a scenario map is created, are these events set at that time, so they are standard for all who play the map? Or if you replay a map could the disasters occur at different times, and possibly different frequencies? In the map editor one simply sets these events by yes or no, yet in my experience there can be enormous variation in frequency from map to map. For example, I am most of the way through playing the career Caesarea map. After 13 years I have had only one mine collapse. In contrast when I played Sarum in the CBC contest last November (same empire state) the mine collapses were so frequent that it was not unusual to have the same mine go down two or even three times in one year, sometimes even in consecutive months.