over 4 years ago - Crater Creator - Direct link
When there's a collapse after several days of being stable, historically it's usually been a rooftop garden at fault. The plants grow, which adds weight and causes the collapse. I'm not sure if that's still a thing in A18, but it's what immediately comes to mind.
about 3 years ago - Crater Creator - Direct link
Originally posted by Arctic Ice Fox: Me and my friend had the same "bug" its the whole weight system. Crop plots are bad at supporting weight (dont know the numbers off the top of my head) and sometimes when the game reloads a chunk something goes weird and they fall in. We found that by putting wood/concrete/cobble plates below the crop plots it fixed the problem entirely.

Wait, so what did you have before that fix? A ceiling composed solely of farm plot blocks?