Events on the map and how are they activated?

[Кот в сапогах]

I noticed that on the Wakanda map at several points there are symbols that at some point were activated. After that, a mini-event with destruction or something like that began. But I still don't understand how they are activated. Can someone explain it to me? Thanks in advance.

[ele]

I think when capture reaches certain point. Haven't really taken notice though.