When it comes to earthquake countermeasures, the issue of what to do with concrete block walls --a familiar element of our daily lives -- has been left untouched. Methods to secure safety must be found urgently.
One week has passed since the earthquake that recorded up to lower 6 on the Japanese seismic intensity scale of 7 near its epicenter in a northern area of Osaka Prefecture. The quake left as many as five people dead and more than 400 people injured. More than 8,000 houses were damaged, and more than 200 people are still living as evacuees.
There is a danger of partially damaged houses collapsing with a minor shock. Precautions against aftershocks must not be neglected.
The latest quake has brought into question the danger posed by concrete block walls. A concrete block wall measuring about 3.5 meters high collapsed at a municipally run elementary school in Takatsuki, Osaka Prefecture, killing a girl student who was trapped underneath it. The height of the wall exceeded the 2.2-meter upper limit set by an enforcement ordinance of the Building Standards Law, and there were no buttresses to shore up the wall.
During an inspection made in accordance with the Building Standards Law, technicians responsible for safety checks did not examine the wall. At one point the wall was judged safe merely through visual inspection. Although an outside expert had pointed out the danger of the wall coming down, the city's board of education did not implement any countermeasures. The prevailing view that this is a man-made disaster is reasonable.
Prompted by the Great East Japan Earthquake, quake resistance work at schools has progressed rapidly. According to the Education, Culture, Sports, Science and Technology Ministry, such work has been completed at 99 percent of the about 117,000 school buildings and the like at public-run elementary and junior high schools. Even for suspended ceilings inside such structures as gymnasiums, measures to prevent them from falling have been implemented at 97 percent of the total.
Safety precaution vital
Regarding concrete block walls, however, their actual condition had not even been ascertained. It should be said that people on the front line of education were insensitive to the danger.
The education ministry has called on schools to make emergency inspections. At schools in various areas of the country, concrete block walls have been found that do not meet safety criteria. Repair work or replacement with a metallic fence, for instance, should be carried out swiftly. If it is difficult to implement such work anytime soon, it is important to keep children away from such walls.
Even at ordinary houses, a great number of the walls may have safety problems. During the latest quake that rocked northern areas of Osaka Prefecture, an 80-year-old man was fatally trapped under a collapsed concrete block wall of a private house.
The danger from the walls came to the fore at the time of a 1978 earthquake off Miyagi Prefecture. During that quake, nine people died because they were trapped under collapsed concrete block walls. After this, the enforcement ordinance of the Building Standards Law was revised. But even quakes that occurred after the revision have resulted in lives lost.
In its prediction of the damage that would result from a major quake expected to strike directly beneath Tokyo, the government estimates there could be 117,000 cases of collapsed concrete block walls and the like, with up to 500 people presumed dead as a result. Collapsed walls will block the roads, impeding evacuation. The entry of emergency vehicles would also be hindered, thus interfering with rescue operations.
There are also local governments that assist people with the expenses of having their concrete block walls removed and replaced with hedges and the like. Owners of concrete block walls, for their part, must be aware of the danger posed by such walls and respond appropriately.
(From The Yomiuri Shimbun, June 26, 2018)
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