Mining is undoubtedly dangerous work, but some tactics are riskier than others. When you look at stories of previous mine collapses, you can see what methods put miners in harm’s way.

One of the standard tactics for mining coal is called “room-and-pillar” mining or the “room-and-pillar method.” Essentially, it means extracting coal from the ground in a way that creates a cavern — the “room” — and leaves pillars of coal behind. These pillars then help to support the roof and allow people to work within the room until the supply is exhausted, or it is time to move on.

That’s where retreat mining comes into play. Miners have to partially remove these enormous pillars. This can make the room less stable and risk a collapse. Some have gone so far as to call it the “most hazardous coal mining activity.” Even so, it is a common tactic.

Why is this? The answer, as you may have suspected, is money. Retreat mining brings in roughly 10 percent of all the coal gathered from underground mining. Not doing it would leave a huge source of potential income underground. Mining companies know that the valuable resource is there, and they have already done all the work to expose it. Extraction is the next logical step, and they are willing to take the risk for the revenue that it provides.

Have you gotten injured in a mining accident or a collapse? Have you lost a loved one in a tragic underground accident? If so, make sure you know what rights workers have to compensation in California.