[Lonesome in Massachussets]

4.) Construction on a barrier island.

https://www.nbcnews.com/news/us-news/cause-miami-condo-collapse-unclear-experts-say-barrier-islands-present-n1272316

[Alan Rumack]

4.) Construction on a barrier island.

That is indeed a thing that is fraught with hazard, as they found out on Padre Island a few years back:

Ocean Tower

And its demolition