THREE great natural disasters in American history dwarf all others in terms of loss of life and property. The most recent is the best known; 450 people died and more than 3,000 were injured in the San Francisco earthquake of April 1906. Less familiar is the hurricane that struck Galveston Island on the Texas coast off the Gulf of Mexico in September 1900; the death toll there, mainly due to a massive storm surge that inundated the entire island, was over 6,000. And the third great natural disaster is rarely heard of nowadays: the Johnstown Flood took place 108 years ago today, on May 31st, 1889.
The Johnstown in question is a quiet town in Pennsylvania in the valley of the Conemaugh River, and at the time of the tragedy it had a population of slightly over 30,000 people. Nearly 40 years before, in 1852, a dam had been built on the river some miles upstream of Johnstown, to supply water for the proposed Pennsylvania Canal. As it happened, the canal project was later abandoned in favour of railway, but the dam remained and the reservoir behind it was used for many years for recreational purposes. It covered 450 acres, and when close to full it was 70 feet deep, two miles long, and a mile across at its widest point.
Rain began on the evening of May 30th, 1889. It continued steadily through the night, becoming heavier and heavier as time went by, and falling in amounts greater than anyone in the area had ever seen before. By the following morning the Conemaugh had burst its banks, leaving Johnstown under several feet of water. But worst was still to come.
By 3 pm on May 31st, the pressure of millions of tons of water became too great for the restraining earthworks of the Johnstown dam. Suddenly the structure dissolved into a great mass of mud, and the contents of the vast reservoir surged down the valley onto the hapless population of the town below. It took only 45 minutes to empty, the swirling waters sweeping away everything in their path.
The debris carried along by the deluge created a vast 32 acre island in the centre of Johnstown, and this pile of devastation became a temporary refuge for many of those who survived the first surge of the flash flood. But their sanctuary was brief; the debris caught fire, and many of those who had survived the flood succumbed to the ensuing inferno. Before the end of the day the Johnstown disaster had claimed the lives of more than 2,000 of its citizens.