You might want to be careful what the earth underneath you is doing if you're driving through Illinois today as a massive sinkhole suddenly opened up and even caused a highway to close.
I'm going to ask what I admit is a bit of a rhetorical question. Why did a huge sinkhole suddenly appear in the woods of Missouri? I have no idea, but I do have video proof that it happened.
I will confess that I only think about sinkholes when I see one appear and that's not frequently. There have been some that have been spotted in Missouri recently which led me on an investigation where I learned that the state is a dangerous sinkhole hotspot.