A different kind of terrain question

This isnt about just destroying terrain ala the numerous scorched earth / worms examples

I’m looking for ways to go about mimicking the original DOS scorched earth where the terrain falls and fills in the holes / area beneath.

For those that have not played the original, picture a mountain in 1 of the current flash games, and keep shooting in the middle. Eventually you will end up with an apple core looking mountain. In the original any overhanging earth would slide down and fill up what is underneath (sometimes that meant your tank got buried which was fun)

This engine, while not flash, has the effect I was looking for
http://julianvidal.com/X/processing/snow5/ (draw a line and hit G)

Any ideas/guidance for me to explore in AS3?