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. Seventeen years earlier, however, more than 2,000 citizens of Johnstown, Pennsylvania, perished following the rupture of a dam on the Conemaugh River after several days of heavy rain in May, 1889.
But the most lethal natural disaster on the North American continent occurred 100 years ago today, on September 8th, 1900. A major hurricane scored a direct hit on Galveston Island on the Texas coast of the Gulf of Mexico; it destroyed 3,600 houses and killed nearly 8,000 people, about a sixth of the entire population.
For almost a week before it hit, there has been successive reports of the storm as it made its way across the Caribbean, passed directly over Cuba and headed into the Gulf of Mexico. By dawn on September 8th, huge waves were battering the coasts near Galveston; by noon the strong winds, accompanied by heavy rain, had brought down telegraph poles and severed communications with the outside world; by mid-afternoon flooding of the electric power plant and the gas works left the city without light; and at 5.15 p.m. the anemometer carefully tended by the resident US Weather Bureau meteorologist disintegrated, but not before it had recorded gusts to 120 m.p.h.
But worse was still to come. Often the most lethal aspect of a hurricane is the large and sudden rise in sea level - the "surge"- which occurs as the eye of the storm approaches land. The surge is produced by a combination of the sudden reduction in atmospheric pressure and the very strong winds which tend to "pile up" sea water against a coastline. The ultimate height of the surge depends on several factors such as tides, the shape of coastline in the vicinity, the intensity of the hurricane itself, and the speed and angle at which it approaches the shore. Typically, however, a raised dome of water 10 to 15 feet above the normal tide level, and some 40 to 50 miles across, might be expected. So it was at Galveston, and it was the surge that caused many of the deaths.
The full story of the Galveston hurricane is told by Eric Larson in a book now widely available called Isaac's Storm. The Isaac in question is Isaac Cline, the weather man who lost his anemometer and who suffered tragic personal loss as well - but to know more of this, you will have to read the book.