What are the causes of Sinkholes and how do Sinkholes form?

Sinkholes explained via model

How is it possible for the ground to just open up and in all directions swallow anything or anyone that happens to be in the approximately? The simple answer is the interaction of water and the ground, it sounds too simple, but we've seen it all over the internet and news.

We already know about erosion, the process that takes soil and rock to move somewhere else and there's a lot of ways that this can happen: wind, landslide, abrasion, scour, and water is the great cause of erosions, the ground is shaped the way they are, more often than not, the answer is pretty much just water.

Now, erosion can also occur in the subsurface as well it's called "internal erosion" natural sinkholes happen in areas with large deposits of carbonate rocks, like limestone. Over long periods of time, groundwater flowing through the subsurface can dissolve the stone, creating voids and open tunnels (caves).

But not every sinkhole is formed through natural processes. In fact, many of the most famous sinkholes in recent times have been human-created. Just like a cave dissolved into the bedrock can act as a pipe and allow groundwater to carry away soil, an actual tube can do the same thing.

Source: Practical Engineering