Nope, they just become less predictable. Which is why in some parts of Germany you can’t build as much as a garden shed without having EOD check the land first. In the more heavily-bombed areas it’s not unusual to hear on the radio that you’re to avoid downtown today between 10 and 12 because they’re disarming a 500-pound bomb they found during roadwork.
And yes, the fact that an unstable bomb capable of trashing a city block is mundane nicely illustrates war’s potential to fuck things up for generations.
Japan might want to get that land under and around the airport checked. There might be some other surprises hidden down there.
Pretty much business as usual. Those things pop up every once in a while, which is why Germany has no shortage of experienced bomb disposal experts.
And yes, the fact that this is perfectly mundane is chilling if you think about it. That’s how intensely bombed areas work for decades. Battlefields don’t turn back to normal when the war is over. And we casually do this all over the world for a large number of usually stupid reasons.