Craters Links: en.wikipedia.org
By: hhgygy
World's largest permafrost crater
First observed in the 60's, it is already more than 1 km long and more than 100 m deep with the perimeter increasing by about 10 m per year.
Craters Links: en.wikipedia.org
By: hhgygy
Detailed research here https://bombarman.livejournal.com/34505.html
at the end of the topic there is a link “Continuation 4”, I wrote about it there (where are the screenshots of Antarctica)
But it’s better, of course, to read the entire study.