July 10, 1926: The Day Nature Blew up a Town in New Jersey

88 years ago today, an explosion of almost unbelievable proportions rocked northern New Jersey, killing nearly two dozen people and shaking the military to its core. The cause was neither criminal nor was it an act of war, but rather a single bolt of lightning.

The air that Saturday was as hot and muggy as one would expect for the Mid-Atlantic in July. The temperature a few miles to the east in New York City sat at an uncomfortable 80° and it was only 8 o'clock in the morning. Even through the oppressive heavy, mid-summer atmosphere, nobody could imagine the disaster that would strike just a few hours later.

July 10, 1926: The Day Nature Blew up a Town in New Jersey

An area of low pressure spun just east of Lake Huron that morning, with a cold front extending to its south through the Ohio Valley and a warm front stretching east through northern New England. Much of the East got caught in the southerly flow behind the warm front, pumping in uncomfortably humid, warm air from the southern latitudes.

The weather forecast for the area reflected the unstable airmass. According to the Weather Bureau, northern New Jersey could expect "thundershowers this afternoon or to-night; considerably cooler to-night." In other words, forecasters expected thunderstorms to develop along and ahead of the approaching cold front on Saturday.

One of these thunderstorms moved over Rockaway Township, home to the Lake Denmark Naval Ammunition Storage Depot and part of the larger Picatinny Arsenal. Roughly halfway between the United States' involvement in World Wars I and II, the military used the depot to store millions of tons of ammunition and explosives left over from the first great war.

Shortly after 5 o'clock in the evening, the thunderstorm produced a bolt of lightning that struck the storage depot at Picatinny Arsenal.

July 10, 1926: The Day Nature Blew up a Town in New Jersey

More than 600,000 tons of explosives stored inside the depot detonated, resulting in one of the most catastrophic man-made explosions in the United States. The blast completely destroyed nearly 200 buildings in a half-mile radius, resulting in $47 million in damages (more than $631 million today when adjusted for inflation), 21 deaths, and dozens more injuries. The explosion was so powerful that people reported finding debris nearly 22 miles away.

The pictures taken after the explosion show what little remained of the arsenal surrounding the depot.

July 10, 1926: The Day Nature Blew up a Town in New Jersey

July 10, 1926: The Day Nature Blew up a Town in New Jersey

July 10, 1926: The Day Nature Blew up a Town in New Jersey

July 10, 1926: The Day Nature Blew up a Town in New Jersey

July 10, 1926: The Day Nature Blew up a Town in New Jersey

The incident at the Picatinny Arsenal prompted the United States Government to get serious about explosives safety. Shortly after the explosion, Congress created the Department of Defense Explosives Safety Board, a board that exists to "provide oversight of the development, manufacture, testing, maintenance, demilitarization, handling, transportation and storage of explosives" within the military.

Lightning striking a building is far from uncommon. Between 2007 and 2011, the phenomenon set fire to an average of more than 22,600 structures each year. Just this week, lightning destroyed 9 oil tanks in North Dakota after the bolt caused an explosion. Many newer and larger buildings have lightning protection systems built into the exterior, drawing lightning into lightning rods and sending it down into the earth through metal cables, to protect the structure from catching fire. Sometimes these modern protections don't work. Lightning struck a group of modular classroom buildings at a middle school in Maryland yesterday, setting ten classrooms on fire.

Unfortunately for the Picatinny Arsenal, these advanced lightning protection systems didn't exist back in the 1920s, but the incident ultimately led to higher safety standards and helped to prevent future catastrophes.

[Images via Found Flicks, NOAA, and John W. Rae's book Picatinny Arsenal]