It's not just the tannerite detonation, as stated before, he compounded the issue by "packing" it into a metal container (the lawnmower).
He made a really nice pipe bomb, of sorts. The initial explosion was compressed by the metal lawnmower, not allowing it to vent.
The pressure was contained and compressed until the metal fatigued - even for a few thousandths of a second....resulting in much bigger and focused explosive event. The metal lawnmower parts just went where the blast sent it.
I feel sorry for the man, losing his leg. But he seriously underestimated the physics of the blast he was creating.
oljames3's 155 mm howitzer shell has such a destructive blast radius; the explosion is contained within the shell for a few thousandths of a second to create a serious over-pressure explosion fragmenting the shell and sending metal shards flying at several times the speed of sound.
Warnings are for cautions people. Reckless folks will never read them in the first place. Maybe he'll keep someone else from doing the same thing.
In NC, where I'm from, most of these stories begin with..."Well, me and Delbert was drinkin' and....".
Which is a very good explanation of how a 'deflagration' becomes a 'detonation' leading to an 'explosion'...lol.
Being an Ammo Tech, we played with stuff that goes 'boom' quite a bit. We generally didn't underestimate the effects of our commercial explosives.
I DID underestimate one once that involve a gallon can of sliced pineapple...lol. In the Gulf War, we burned our trash in holes. When we got hot chow for breakfast, they always brought a few gallon cans of sliced fruit. I was one of the only ones that generally ate any of it so I tended to collect cans of the stuff in excess of what I actually ate...
I was burning the trash one day about 45 feet from the truck where my buddies were occupied with our primary pastime out in middle of nowhere...spades. I set one of those gallon cans in the edge of the fire hole and waited. That sucker went off blowing the lid off the can and sending sliced pineapple for about 35 feet (it went farther than I figured it would...but in the intended direction though...lol.) When that can went off, those marines around that card table came un-glued!
They didn't find it as funny as I did...lol.
A man will fight harder for his interests than for his rights.
- Napoleon Bonaparte
PFC Paul E. Ison USMC 1916-2001