Elder ring of death question

The wiki entry for the elder
https://www.poewiki.net/wiki/The_Elder
says that one needs to stay *within* the "immer circle" of the blast radius to survive.
What does that mean?
So it's not the intuitive solution to just run as far as possible away, but one must stay as close as possible?

Yes. The small circle in the middle is the safe zone when it detonates

The aoe isn't just a regular circle. It's donut shaped.



Seems pretty intuitive to me and most games with boss fights have such a mechanic at some point but it's especially common in roguelites and MMOs.

Thanks much. I realize I'm quite poor at these things, so thanks for your patience.
To not screw up again:

Survive =
1. be inside the very inner ring (the "empty part" of the "donut" "hole")
AND
2. be outside the very outer ring (completely outside the donut)

Are both ok or only #1?

Both are fine but the ring expands and might push you against a wall depending on positioning. It's generally safer to just hug the boss.