We have similar, though not as large, ones here in AZ, that are largely caused by water table erosion. The water table drops, and soil compacts under its own weight. You have larger and larger gaps down below as sections of soil drop, making several gaps that slowly move upwards. At a critical point, the surface drops, and some of the gas escapes. at that point, pankcake scenario, as well as dirt filling into gaps down below, natural caverns, ect.
When you add that they are having volcanic activity right now, gas pockets and moving underground soil and bedrock creating gaps seems extra plausible. On Tue, Jun 1, 2010 at 1:00 PM, Jed Rothwell <[email protected]> wrote: > See: > > http://www.cnn.com/2010/WORLD/americas/06/01/central.america.storm.deaths/ > > This is mind-blowing. I do not see how such a giant hole could form with > this shape: a giant, deep, round shaft, big enough to swallow up a 3-story > building. > > Sinkholes are common in Georgia and Florida but I have never heard of one > like this. As far as I know they are caused by an underground flow of water. > The water hollows out a volume of earth which then collapses from above. I > do not see how it could hollow out such a huge volume without the collapse > occurring earlier than it did. > > In Atlanta, antiquated sewer and broken water lines cause sinkholes and > sudden collapses. Several years ago one opened up suddenly in a parking lot > downtown, where dirt and asphalt had been piled on top of the pipeline for > years, finally breaking it. The hole opened suddenly and a pedestrian fell > in and was swept away. I do not think the body was ever found. It sounds > like something from a horror movie but it really happened. > > - Jed >
