Here's the consequences of a similar sized (75mm) WW1 trophy shell detonating, in 1922.
Madera Mercury 13 July 1922 — California Digital Newspaper Collection
Pine Camp was the first name for what is now Fort Drum - which I have spent a LOT of time at. Sad story but exactly what can happen.
With a dud or misfire you never know what/when might cause a detonation.
I believe it was May of 1982. I was the S3 (Operations Officer - which made me in charge of training) of a National Guard combat engineer battalion. We were at our 2 week annual training - strangely enough not at Fort Drum but at Indiantown Gap which is outside Harrisburg, PA. We had a hand grenade range going. Hand grenades have a tendency to get untrained people in trouble - and I have seen cases where the nerves can get to someone. As it was the most dangerous training we had going on right then I was there to make sure it went off safely. As I remember that range had 6 positions. Once you have it going there is a rhythm to it with the commands, thrower stands up, throws the grenade, drops back into the pit, etc. Three seconds after the throw command you should hear the detonation of the grenade. Things were going nice and smooth, I'm a safe distance behind the range tower that is controlling things - so I break out my thermos, pour a cup of coffee and am sitting on the hood of my quarter ton. Hear the boom in sequence - then three seconds later another boom behind me and to my left. WTF - call a check fire to range control to shut down all live fire. To make a long story short - we ended up with every strap hanger and horse holder on the place there and EOD (bomb disposal) comes out. From what is found where the explosion happened it was a fragmentary grenade like we were using. EOD does a search down range on the range and finds three other dud grenades out there. Now on a range if you throw a grenade and nothing goes off the rule is you shut down, call range control and EOD. After the safe waiting period EOD goes out, finds it, puts a charge next to it and blows both up. One or more previous users had duds and just left them. It was just our luck that one of the guys landed a grenade close enough to the dud that it kicked it up in the air sending it back and over the firing line and at the same time setting the fuse burning. I'll leave it to you to figure the probability on that chain of events. One of my guys actually got a small piece of the frag grenade in the back of his leg - barely drew blood. But we were lucky. It could have just as easily dropped into one of the pits - or in my coffee.
That is just one of the reasons I have a healthy respect for such things. I'm not scared of them - but you have to have respect. Live firing, demolitions, aviation and other such activities are not inherently deadly but they are VERY unforgiving. You need to know what you are doing and have respect. Rolling the dice with unknowns is not worth it.
And if I could have gotten my hands on the SOB range officer that left the duds there I would have shoved them down his throat.