Hello,
when i lived in Goettingen there were 1-2 bomb alarms every year. Two of them went off by themselves, fortunately no one was hurt. One went up at night under a fair, only damaging the ferris wheel and a few whirligigs and carousels.
One problem are the delayed fuses, and the acid mechanism coming of age.
From Mr. Weise, a bomb technician:
"In the last few years we’ve found that the detonators we take out of such bombs are increasingly brittle," Weise said. "Recently we’ve had three extracted detonators go off with a pissssh sound while they were being transported away, all it took was a bit of vibration. One day such bombs will be so sensitive that no one will be able to handle them. We may have to stop defusing them as soon as next year."
From the commentary:
" ... Several people have been in injured in spontaneous bomb explosions in Oranienburg over the years and experts have warned that with the passage of time such detonations are becoming more likely.
An estimated 20,000 delay-action bombs were dropped on Oranienburg during the war because it had a suspected atomic bomb research site, the Heinkel aircraft factory and a pharmaceutical plant. They were designed to explode between two and 146 hours after hitting the ground, to disrupt clearing up work and cause chaos. ..."
A lot of those never exploded, but will sometime in the future.
Greetings,
Catfish