Sink Holes as big as a skyscraper and as wide as a city street open up on the Arctic sea floor. See https://www.livescience.com/sinkholes-opening-arctic-seafloor … there is no link to a research paper but presumably it must be somewhere out there on the Net. The main thrust at the link is that submerged permafrost beneath the Arctic Ocean is causing huge sinkholes to emerge – but could this be down to natural gas seeping too? It is not that far off as we are told that the blame is all about heating from below – not by gas but by slowly moving groundwater systems. Perhaps it is a combination of both gas and warm water. The Arctic Ocean, as we know, has hydrocarbon reserves, exploited by both the US and Russia. However, there is a difference in provinence as these sink holes are in Canadian waters – and global warming is very strong in Canadian politics.
Moving away from that it is worth having a look at more mundane sinkholes. Go to https://livescience.com/44123-what-are-sinkholes.html … this is an older post, from 2017. It has a general look at sink holes. They’veswallowed cars in Kentucky, combos in Florida, and houses in Texas. Over here in the UK they tried to munch down a double decker bus, and have swallowed a car park. What causes the collapse of solid ground? Water is one of the suspects – gradually washing away sediments and soft rock. That also includes leaking water pipes and sewage systems – and lots of rain. Heavy and persistent rainfall will soften up the ground nicely. However, mine workings can also cause a collapse. There was a big one in Louisiana in 2012 as a result of an underground oil reservoir. Mine shafts have collapsed in Australia and almost anywhere else in the world, and clay pits are another problem. Nothing like the huge sinkholes in the permafrost – but a common occurrence wherever humans have been looking for minerals to exploit.