The researchers used special techniques to study how the ground moves and breaks during coal mining. They found that by using a combination of borehole photography and seismic scanning, they could see where the ground was breaking and caving in. This helped them figure out how to control the ground above the coal mine better. They discovered that in one mine, the top of the broken area was 171 meters deep, and the fractured zone was between 106 and 110 meters deep. This information can help make mining safer and more efficient.