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!

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

closeAuthor: Shane Sakata Name: Shane Sakata
Email: shanesakata@gmail.com
Site: http://www.nihonsun.com
About: 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 writes about Japan travel & culture at The Nihon SunSee Authors Posts (2)