I do not like to necessarily post about every sinkhole that is reported in the news, but this is a big one.
Apparently, the geology of Canada is much akin to those areas in the United States impacted by sinkhole activity.

After reading this, I called a geologist who I know has done a lot of work throughout North America.  His comment about Canada is that it has much of the same overall geology as we find in areas in the United States where sinkholes are present.  You are going to look for shallow limestone or clay soil conditions and a rising and falling water table.

Sinkhole activity, he said, is about soil density.  When conditions such as this are present, you can see dramatic catastrophic collapses such as that shown in this video.