There had been warnings about mines, Sergeant Alva said, but the general feeling was that most of the mines had been cleared from the area where his convoy was moving.
Without warning, the mining chamber's ceiling collapsed, instantly killing three miners.
It can also provide disaster early-warning for mine production.
The authorities also distributed pamphlets, which carried photos of the North Korean mines, warning people living near the border not to touch objects that look like the land mines.
"We ask all citizens to respect all signs warning them about mines and to not enter areas unfamiliar to them".
Then, like a final warning, the remaining mines went off at 7 28 a.m., followed by a two-minute wait to allow the debris -- blown thousands of feet into the air -- to fall back to earth before British troops climbed out of their trenches to advance.
If not, it is either flagged as yellow, a warning to the mine to resolve minor issues, or red, which bars the mine from producing minerals for at least six months, or until another inspection can be conducted.
Are artists the canaries in the mine, warning of the coming explosion before anyone else?
It should also be a warning to the mining industry that the days of getting its way, no matter the cost, are over.
At the end, Strangelove leaping out of his chair, and General Turgidson warning of a "mine-shaft gap" with the Soviet Union, are continuing their assertion of high acumen.
