On this day May 4, 1988, a massive explosion (comparable to a small nuclear blast) at the Pacific Engineering Production Company of Nevada (PEPCON) rocked Henderson, Nevada, just outside Las Vegas. 4000 tons of aluminum perchlorate (an oxidizer for rocket fuel) detonated, killing two and injuring 372. The first explosion in the video below is just a precursor. The big one is at about 1:04. And unlike some videos of this I’ve seen, the sound hasn’t been edited to align with the blast. From this vantage point two miles away, the shock wave takes just over ten seconds to arrive.