Unexploded WWII Bombs In Japan - How Many Are Out There?
By Shane Sakata • May 23rd, 2008 • Category: The Latest
On March 27th an unexploded bomb was found in the Tokyo suburb of Chofu by construction crews. It is suspected that the B-29 bomber carrying the ordinance collided with a Japanese Hien fighter plane on April 7, 1945 before it had an opportunity to deliver it’s payload. A 63 year old resident of the area was a junior high school student at that time and sketched the crash in his diary and returned the following day to sketch what remained of the B-29 bomber. Researchers compared the sketch with the flight records of the Hien fighter that crashed that day and confirmed the connection.
Although the bomb was located on March 27th it was not diffused until this past Saturday, May 18th. The one-ton U.S. made bomb was buried 3.25 meters underground and is about 1.8 meters long with a 60 centimeters diameter. Like me, you may have though why did it take almost two months for the bomb to be diffused and what were the potential risk to the residents of the area should it explode?
The Daily Yomiuri reported that “after the bomb was discovered, the Self-Defense Forces took swift measures to secure the area and a security company is monitoring the bomb around the clock. ” The city issued an order which resulted in the evacuation of about 16,000 people from approximately 8,000 households within 500 meters of the bomb to leave their homes on May 18 for the duration of the disposal work.
So for almost two months 160,000 residents were living, working and playing around a ‘heavily secured’ 1-ton bomb that if it were to explode above ground would send shrapnel and debris over a two kilometer area! I’m not a scientist but these numbers concern me. The evacuation area was 500 meters in diameter when the potential area of damage could have been a large as 2 kilometers. Would the 3.35 meters of dirt covering the bomb reduce it’s impact by a quarter? What if there had been a large earthquake between March 27th and May 18th? Could the rumbling have set off the bomb?
This is not an isolated incident. Here are some other recent cases:
- About 10,000 residents of Higashi-Nada Ward, Kobe, were issued with an evacuation order in March 2007.
- A 300 meter area of Osaka was evacuated in April to dispose of a bomb found by construction workers.. It was the 97th one-ton bomb discovered and defused in Osaka since the end of World War II in 1945.
- In fiscal 2004 alone, Defense Agency bomb squads defused 146 tons of explosives reported in some 2,600 cases. Anywhere from 1,600 to more than 3,000 cases are handled each year.
Between 1939 and 1945 the Allies dropped 3.4 million tons of bombs, an average of about 27,700 tons of bombs each month. It is hard to determine exactly how many tons of bombs were dropped on Japan during WWII but some estimate that up to 30% of the bombs dropped did not explode on impact. How many more unexploded WWII era bombs are still out there undiscovered? What is the danger to the public? Should the time from discovery to diffusion be less than two months?
I don’t have the answers to the first two questions but I know for sure that if I found a bomb in my back yard I would hope that it wouldn’t take the government two months to remove it!
Tokyo unexploded bomb news footage
Sources:
Mainichi Daily News, Man’s 63-year-old sketch pinpoints dud WWII bomb
Daily Yomiuri, Tokyo area to be evacuated for WWII bomb defusal
China Daily, World War II bomb clearance may need 150 years
World War 2. info, World War 2 Facts
Japan Times, Remnants of war still buried in Japan
The story continues: read here
Shane Sakata is a resident of Mihama in Chiba, about thirty minutes outside of Tokyo on the JR Keiyo Line. Shane grew up in Burnaby, British Columbia, Canada and then moved with her husband to his home state of Hawaii in 1994, which is where she calls home when she’s not in Japan. From Hawaii it was on to Japan where she spent the better part of four years from 1994-1998. She is now back in Japan and sharing all that she learns about the things to do and see in the Tokyo metropolitan area at The Tokyo Traveler: http://www.thetokyotraveler.com
Her personal blog is at: http://www.atypicallife.com
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Unexploded Bombs in Japan!…
An unexploded bomb from the WWII era was found in Tokyo in March. What dangers are posed by these silent relics?…
“Between Nov 1, 1944 and Aug 15, 1945 American B29 Superforts dropped more than 11,000 bombs weighing 500 or more pounds on Tokyo alone, destroying 51% of what is now the worlds largest city.”
Historically 5-20% of military high explosive munitions fail to function as intended (duds). So how many unexploded bombs failed to explode and buried themselves in the ground? Pick a number between 500 and 2200.
There is another possible category of unexploded bomb. WW11 bomb fuses were allowed to arm when an arming wire was extracted from the arming vane (little windmill) allowing it to rotate and arm the fuse. If the bomb came out of the plane without the arming wires being extracted the bomb would impact the ground without detonating leaving a penetration hole not an explosion crater.
This could possibly happen if a plane, (on its way to target) came apart in the sky and plummeted to the ground as the plane carrying the Chofu bomb did. The only reason I consider this a possibility is that there are no reported bomb detonations in the eyewitness account of the event.
According to Mr Keizo Okada,s eye witness account: “the Hien slammed into the B29,s engine….The B29 broke apart in the air and plummeted to the ground..”. No mention of any bomb detonations in connection with the event.
The B29 Superfortress had a bomb payload of 20,000lb.
The Shinten-Seiku-Tai “Shuddering Sky” Air Superiority Unit flying the Kawasaki Ki-61 Hien knocked down numerous B29s with their Taiatari “body crashing attacks”.
I do not think the 2 months it took to arrange for and coordinate the evacuation of 16,0000, people, stopping of train traffic and suspending all business activity to be unreasonable, the bomb had been there for 63 years shaken by both earthquakes and train traffic without detonating.
Give the JGSDF EOD some credit they are very experienced and professional they have conducted similar operations countless times.
I was US Army EOD stationed in Japan during the 1960s.
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Thanks for the comment, Roy. Your perspective is definitely appreciated.
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Roy,
I really appreciate the time that you took to research your comment and I think that is great information to share with the readers of this article. You taught me something too - very interesting! Thank you.
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Shane,
I have never responded to a Blog before. I came across this one and was impressed with your layout and the question: “How Many Are Out There?”.
I have seen many newspaper articles about disposal of unexploded bombs but this one was different, there was an eyewitness to the event “Man,s 63 year old sketch pinpoints dud WW11 bomb”
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Frankly I am skeptical, that this bomb came from that B29.I think it is quite a coincidence that this bomb was ejected from the rammed B29 and penetrated the ground right next to railway tracks. The highest concentration of large unexploded bombs would be around military installations, factories, railway lines, railway stations, railway switching yards, important bridges, port facilities and warehouses. However the bomb came to be there makes no difference the question in my mind is: Was this a previously recorded suspected unexploded bomb location?
After bombing raids civil defense would survey the bombed area looking for unexploded bomb impact craters, these craters could then be probed with a long non-magnetic rod to find the hole of entry of the bomb. The angle of the probe in hole of entry would also indicate the direction the bomb took after penetrating the ground. The suspected unexploded bomb location was recorded. Some unexploded bombs would penetrate the ground and come back up to the surface
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I have a picture of a map marked by the Japanese police immediately after an attack during WW11 indicating the locations of unexploded bombs. Were all unexploded bombs accounted for in this way? I would guess that great many were not.
The Japan Times article “Remnants of war still buried in Japan” reporting about a bomb disposal operation in Nishitokyo is very interesting, it mentions an 84 year old lady that knew about location of that bomb since 1949. It also brings up the subject of cost to local governments for bomb disposal operations.
I was involved in a bomb disposal operation in 1969 that cost the Tokyo Metropolitan Government $38,892 (Inokashiro Park, Tokyo). I would guess that the Chofu operation must have cost well over $100,000.
Please excuse me for rambling on, but one thing just lead to another.
I
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Roy, it looks as if the last part of your comment dropped off which disappointed me. Please feel free to continue it as I have no way of retrieving it. You have first hand experience in bomb disposal in Japan which many/most of us blogging today can draw on when we out together these articles. You were not rambling on - what you have to say is very interesting!
I would love to see the map that you refer to as it is an interesting historical document and I found your description of how the bombs were located very informative. In this day and age you would think that they could use some sort of ground penetrating radar or x-ray technology to more easily locate the buried bombs but that type of technology was not available at that point in time.
The other interesting fact that the ‘Remnants of War’ article brings up is that it s not only US munitions that pose a threat but old bomb shelters and abandoned Japanese chemical weapons. Basted on your comments it would seem that the latter two probably pose a greater risk than the unexploded US munitions.
Thanks for reading and commenting Roy.
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Shane,
I was not cut off, that “I” slipped by me. Since you are interested I will continue. I have just been tiptoeing along with my comments about this event. I will comment on the two newspaper articles (Manichi Daily News, “Man’s 63-year old sketch pinpoints dud WW11 bomb” and Japan Times, “Remnants of war still buried in Japan”).
The most interesting part of the Maninchi Daily News article to me was: “Records show the bomb Self-Defense Force explosive experts will diffuse .….came from the plane that plummeted out of the skies after a Japanese pilot rammed into it in his Kawasaki Ki-61 Hien fighter before parachuting to safety” Later the article mentioned that the pilot was a 2nd Lieutenant.
I thought “WOW” that was an amazing event. So I googled “Japanese Kawasaki Ki 61 Hien fighter plane” and discovered some very interesting information about the Hien Ki 61 and the some of the fighter pilots who flew them. In Japanese Aviation, Mark’s Index (www.markkaiser.com) (no relation to me, just another coincidence), I found stories about other pilots who had successfully brought down B29s numerous times and survived. Particular mention was made o St.Sgt. Matsumi Nakano and Maj Teruhiko Kobayashi (‘He rose to fame as the CO of the 244 Sentai defending the skies the skies over Tokyo”). Check out this website it is very interesting.
Going back to the Maninchi Daily News article, I wonder if the reason the 2nd Lieutenant’s name was mentioned is because he did not bring his plane back. It was a remarkable feat to dive into a formation of B29s knock one down and survive.
I then skipped though the google list and on page 9, found “Best Japanese B-29 ‘killer’” (www.ww2aircraft.net/forum/aviation/best-japanese-b-29-killer) A lot interesting information, Maj Teruhiko Koboyashi’s name is mentioned also a list of Japanese B29- Aces “Superfortress killers”. Check out this website. There are several interesting stories.
I will comment on the Japan Times article next time. Interesting that you have brought up modern technology.
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*correction to 4th paragraph - should read “….name was not mentioned”
How do I post a picture of the map?
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Shane,
The Japan Times article “Remnants of war still buried in Japan” dramatically describes the problem Japan has with unexploded bombs (UXB) The part “Please find the bomb though the first paragraph of “burying the problem”. It boils down to economic practicality, cost involved in the excavation and disposal versus risk that the bomb will detonate. So the procedure has evolved of disposing of the UXB on a priority basis or when for one reason or another it becomes a present day problem (“Let sleeping dogs lie”). I would like to revise my estimate of the cost of the Chofu disposal operation to over $500,000.00, based on what the Nishtokyo disposal operation cost 25 million yen ($242,000.00).
I will continue by mentioning some things related to the UXB topic.
Expanding on previous comments looking for UXB (reconnaissance) the bombs that impact the ground and detonate form blast craters these craters are often have a pattern a space where blast crater seems to be missing would be closely examined for a UXB impact crater.
The large General Purpose High explosive bombs dropped on Japan were usually fused:
To detonate on impact (nose and tail fuse), to penetrate the surface then detonate (nose plug and tail fuse), and detonate delayed action up to 144 hours after impact (tail fuse). The delay fuses had an anti-withdrawal feature.
While writing these comments I thought someone must have written a book about Japan’s UXB. I found an e-journal article by Mark Selden “A Forgotten Holocaust: US Bombing Strategy, the Destruction of Japanese Cities and the American Way of War from WW11 to Iraq” It is depressing to read the whole article but I pulled out the following paragraph to show that there are five cities in Japan where UXB are unlikely to be found.
“Between January and July 1945, the US firebombed and destroyed all but five Japanese cities, deliberately sparing Kyoto, the ancient imperial capital, and four others. The extent of the destruction was impressive ranging from 50 to 60% of the urban area destroyed in cities including Kobe, Yokohama and Tokyo, to 60 to 88% in seventeen cities, to 98.6% in the case of Toyama. [33] In the end, the Atomic Bomb Selection Committee chose Hiroshima, Kokura, Niigata, and Nagasaki as the pristine targets to display the awesome power of the atomic bomb to Japan and the world in the event that would both bring to a spectacular end the costliest war in human history and send a powerful message to the Soviet Union.”
If I had to make a choice between working on a WW11 Japanese UXB in China or a WW11 US UXB I would choose the US UXB because the explosives used in the Japanese bombs were very unstable. I bought this up just as a reminder that there must be a lot of Japanese UXB in China.
Modern UXB locating technology: I am not up date on all the latest technology magnetometer is probably useful. Ground penetrating radar has limitations. X-ray technology is useful in some cases if the item is exposed. If oil deposits can be located miles underground it should not be a problem finding a UXB at any depth.
t
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I see a “t” slipped by me this time
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I can make some comments on “Poison gas info scarce” part of – The Japan Times article also, the China Daily article “World War 2 clearance may need 150 years” if anyone is interested.
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Roy, I’d love to combine all of this great information that you have into a new article on this subject. I’ll be contacting you shortly to discuss this.
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Shane,OK. One more comment here:
I have not found any reference to death or injury caused by buried WW11 bombs in Japan. It is hard to believe that none have occurred, but that is the result of my many search efforts.
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SGM Kaiser:
The Goggle search engine found this. Been some time since I thought about the 549th EODCC when we worked together. I remember you mentioning your days in Japan. I also seem to remember Albertson as the guy who had a huge collection of military ordnance.
I still work in the UXO field.
(Then LT) Dick Wright
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