I used to drop bombs for the USAF. Modern, 1980s bombs. I don’t know much about WWII bombs, but the post-impact part of bombs hasn’t changed much over the years.
The standard US sizes were/are 500 lbs, 1000 lbs and 2000 lbs. For each of them, the explosive weighs about 1/2 that much and the metal casing and fins and fuzes make up the rest. Most of the volume is explosive, but it’s not as dense as the relatively thin metal shell.
Here’s a pretty good thumbnail ref on aerial bombs from their inception to today.
A 500# bomb dropped on a typical suburban house would simply convert it to either kindling or gravel, depending on whether it started out as wood frame or brick construction.
Unike in Hollywood, there’s no major smoke or fireball. The house simply disappears in a puff of browninsh smoke. Sorta like a direct hit from a tornado, but with smaller peices remaining.
The immediately adjacent houses would be severely damaged, maybe 3/4ths collased. The next houses would be partly collapsed. The house right across the street, which has once face broadside to the explosion would also be caved in at least partially. All windows would be broken for a couple of hundred feet in any direction, and most windows out to 500-600 feet.
And that’s about it. For a 2000# bomb, double the radius of destruction for each level of effect.
The bomb will not do much to set the wreackage on fire since the explosion happens too quickly to really heat up much of the solid material. But it will ignite any broken natural gas lines and that will feed a fire that will further trash the wreckage or spread the flames to other nearby, relatively undamaged, buildings.
Tthat fire effect was a large part of the reason WWII city bombing was effective. They used lots and lots of bombs like an aerial shotgun to trash enough buildings close enough together that the ensuing fires coalesce into an inferno. And they’d also salt a few incindiary boms into the mix, which don’t do nearly as much damage as the normal blast/frag bombs, but do ensure the wreckage gets well ignited.
That’s also why all the emphasis on precision bombing & smart bombs these days. If you’re trying to destroy a particular building, missing by 50 feet ends up trashing the building’s exterior rather than obliterating it. Inaccurate bombing means you either have to use lots of bombs to improve the odds, or come back again again tomorrow to finish the job. Oddly enough, they bad guys are expecting you next time and will have a suitable reception prepared.
Finally, making a ballistic (“dumb”) bomb land right where you want to while overflying the target at 600 mph while the bad guys are trying to shoot you down is a difficult feat to get right every time. Far easier to toss the bomb in the right general direction and let a computer fine-tune the point of impact.
So returning to the specific bomb in the news story, the problem isn’t that the thing is going to obliterate the town, but rather that if it does go off, anybody right nearby is gonna get hurt and they won’t be happy about it.