1920s postcard of the Lochnagar Crater.

The Lochnagar Crater is 90 feet deep and 300 feet across and was caused by a charge of 60,000 lbs (26.8 tons) of Ammonal explosives that was set off on the German front lines on the Somme on 1st July 1916. Cecil Lewis, an officer in the Royal Flying Corps who saw the mine explode from his aircraft stated;

“The whole earth heaved and flared, a tremendous and magnificent column rose up into the sky.
There was an ear-splitting roar, drowning all the guns, flinging the machine sideways in the
repercussing air. The earth column rose higher and higher to almost 4,000 feet.”

somme-1916.com