If you knew stories about the lake, wouldn't you try to get away from it? And by the pictures away <==> up in most cases. Also, I feel like at least my flight instinct prefers higher ground.

Not saying the 8 survivors didn't know what's up, but stuff like this is definitely how religious stories get formed in general.

Natural instinct is to run away.

It's like how the smart thing to do is run to the side of a tree that's starting to fall over (perpendicular to it's projected fall).

A good way of describing it to the locals might be that 'bad gasses come from the lake and cling to the ground, like a leaden miasma from hell'.

You don't want to be very close to a tree that is falling over because of the way the roots tear up the ground. Or, if the tree has been cut down and its direction of fall is not clear of obstructions, the cut end of the trunk could fly around in unexpected ways. Best to be well clear on the far side of the direction of fall.

Interesting, how they were able to realize what's going on.

Wiki tells that one loses conscience after couple of inhales of CO2.

I assume that those folks went on high ground just after they've heard sound.