This bomb was buried. Nobody knew it was there...which is sort of crazy, considering that they built a runway over it and it didn't detonate until now.
Do they (Japan, Germany) ever purposely leave unexploded ordnance in place? I see a news story about once a year about them finding a bomb, and in every case they have their bomb squad disarm and remove it. I’ve never heard of them knowingly leaving a bomb in place.
Once there's any sort of record that there's UXO somewhere it pretty much has to be removed because nobody wants the liability that would be incurred by being the party that dropped the ball. Even if that wasn't the case they generally get found because they're in the way of some construction. You have to remove it for the same reason you have to get every other rock out of the hole you're digging.
That said, I'm sure there's a few farmers who have a pretty strong inkling where one is and are actively not looking to disturb that problem.
I know of some remote¹ forest in Germany that used to be a training area. It is so bullet- and bomb-riddled that they just decided clearing it wasn't worth it, put a fence around it and declared it off-limits.
¹ in Germany, "remote" means something like "2km from the next settlement".
One of the reasons that the explosives have not been removed was the unfortunate outcome of a similar operation in July 1967, to neutralize the contents of the Polish cargo ship Kielce, that sank in 1946, off Folkestone in the English Channel. During preliminary work, Kielce exploded with a force equivalent to an earthquake measuring 4.5 on the Richter scale, digging a 20-foot-deep (6 m) crater in the seabed and bringing "panic and chaos" to Folkestone, although there were no injuries.[5]: 2000 survey, p21–22 Kielce was at least 3 or 4 miles (4.8 or 6.4 km) from land, had sunk in deeper water than Richard Montgomery, and had "just a fraction" of the load of explosives.[10] According to a BBC News report in 1970,[12] it was determined that if the wreck of Richard Montgomery exploded, it would throw a 300 metres (980 feet)-wide column of water and debris nearly 3,000 metres (9,800 feet) into the air and generate a wave 5 metres (16 feet) high. Almost every window in Sheerness (population circa 20,000) would be broken and buildings would be damaged by the blast.
I don’t think so. Bombs are usually found during construction so leaving them in place would not work if they block progress on a hole/tunnel etc
For reference the state of NRW (Germany) alone found 2811 bombs in 2018 so it’s much more common than you’d think.
Laws seem to differ by state but afaik new construction must include some kind of bomb assessment, often done via aerial photos to quickly filter out areas that were not bombed at all
in every case they have their bomb squad disarm and remove it
They would do that, the pencil detonators the Allies used to disrupt rescue and firefighting efforts after a carpet-bombing run become ever more touchy as time wears on. A bomb that is found is disarmed or exploded, else there will be a repeat of this incident down the line.
I'm not sure. What is to be gained over leaving a bomb buried, if you know about it? Because then, it could go off at any time versus doing a controlled detonation or remotely disarm it.
It was probably buried during WWII where the concern was get this airport working fast so it can be used and deal with the consequences latter. Of course nobody bothered to write down where hidden bombs are (that would take time they didn't have) and so they couldn't deal with it latter.
Looking at the article, this was a WWII air base converted to a civilian airport. The bomb was not paved over due to laziness; no one knew the bomb was there.
Hindsight being 20/20, maybe they (the Japanese) could have used metal detectors when they were updating the runway? But, given that they didn't find this, I suspect it wasn't practical back then.
Perhaps now there will be an effort to use modern technology to find these?
A bomb like this could be pretty deep though. They're pretty aerodynamic and heavy yet compact. They'd go through mud pretty easily. If it's a few metres deep I doubt it would show up on a metal detector. This is why so many are still found.
There's now ground penetrating radar that archeologists use to find chambers deep in pyramids. I doubt it was around when the runway was built, but now there's clearly a case to use it.
