Of the three types the only one that is safe is strip mining.
The vertical and horizontal shaft mining for coal are both exceedingly dangerous and people are killed and injured by both methods.
Ashley Judd prefers that people die while mining coal.
Yep, my uncle (my mom's brother) was killed in 1957 when a large rock fell on him deep in a mine, crushing his skull flat like a pancake. For some strange reason (which I'll never understand) my Grandma insisted on an open casket funeral.
My dad worked underground for 10 years, and then after slipping three disks in his back, spent the last 25 years of his working life running a D-9 Caterpillar bulldozer along strip mine high walls.
Very dangerous work, even at that, since several of his friends misjudged their clearance space and ran their dozers clear off the cliff, plunging to their deaths 300 feet below.