Nearly two weeks after the earthquake and tsunami struck Japan, engineers still do not know the full extent of damage to
roads, bridges, rail lines and other infrastructure.
While much attention has been focused on the crisis at the Fukushima Daiichi nuclear plant, only fragmentary information
has become available about damage to other large complexes, like water distribution and sewage treatment plants.
Even Japanese government agencies and professional engineering groups appear to have limited knowledge of the scope of
the destruction along the northeastern coast of Honshu Island, where the tsunami hit on March 11, and further inland, where
the quake damaged buildings and other structures and caused landslides.
“We don’t understand the real situation,” Hiroyuki Yanagawa of the Japan Society of Civil Engineers wrote in an e-mail. “We
cannot investigate the area.” The group is based in Tokyo, far from the affected region, where entry has been restricted largely
to emergency vehicles.
In the United States, earthquake engineers who often travel to the scene of a major quake within days have been unable to go
to Japan because of concerns about radiation.
Stephen Mahin, a structural engineering professor at the University of California, Berkeley, and the director of the Pacific
Earthquake Engineering Research Center, said that he and others had been planning to go but that the university had
canceled their travel insurance.
He now expects to go next week, but will most likely be limited to Tokyo, about 140 miles from the damaged reactors.
“Inspecting earthquake damage is a risk, but it is a risk we know about,” Dr. Mahin wrote in an e-mail. “Being dependent on
public release of information on radiation hazards (or evacuation orders) that we have little control over is a different thing
entirely.”
The National Science Foundation, which finances field research after disasters and supported an engineering team that went
to New Zealand after the recent earthquake there, said it was accepting proposals for Japan. The review process takes several
weeks.
Some information about infrastructure damage is now trickling out. Incomplete as it is, the information helps explain why
the Japanese government says that apart from the damage caused by the problems at the nuclear plant, recovery will take five
years and cost hundreds of billions of dollars.
The Japanese Ministry of Land, Infrastructure, Transport and Tourism, which had been posting limited information about
road and rail service since the quake, now says all expressways in the region are passable, and that high-speed rail service has
been restored on all but two lines that have long stretches with damage to rails or to overhead electric lines. All airports are
open to commercial traffic except the one in Sendai, where video cameras recorded a wall of water reaching as high as the
jetways.
The ministry reported damage to about 50 sewage treatment plants. Other agencies reported that gas and water distribution
had improved, though there were still many towns with limited or no service. None of the reports outlined the degree of
damage to specific facilities.
Other assessments have been cobbled together by engineers based on reports from local agencies, photographs and, in some
cases, personal observations. Engineers at the University of Tokyo listed 17 bridges that had been washed away by the
tsunami; five sewage plants either damaged or destroyed; flooding at one damaged dam; and dozens of landslides and
deposits of debris that have closed roads. In one case, they reported tsunami damage along an 18-mile stretch of coastal roads
south of Iwaki.
A report by an engineer at Tokai University in Shizuoka, south of Tokyo, was more anecdotal, with photographs of roads
blocked by landslides or warped as the ground underneath them subsided; rail lines tossed about like strands of spaghetti;
collapsed electrical pylons; sewage plants buried in debris; and, in Sendai, huge storage tanks toppled over at a brewery.
A few engineers who study tsunamis lived through the disaster and described the destruction around them. Shunichi
Koshimura, a researcher at the tsunami engineering laboratory at Tohoku University, and others reported that the lab was
effectively destroyed and that much of the university was heavily damaged.
A day after the quake, Dr. Koshimura, who published a study last year about coastal effects of the 2004 Indian Ocean tsunami,
tried to conduct a field study by car of the damage in the flatlands around Sendai but was turned back by debris and water.
Kit Miyamoto, an earthquake engineer born in Tokyo and living in San Francisco, was in Tokyo when the quake occurred. His
flight home delayed and able to obtain the necessary permits, he drove up to the affected coast.
In an interview, Dr. Miyamoto described coastal rail lines that were swept away by the tsunami, and said the vast majority of
the buildings that were destroyed were made of wood. “Almost all concrete and steel structures survived,” he said, though
they were often heavily damaged.
Dr. Miyamoto said some infrastructure in the area appeared to make the disaster worse. In the city of Rikuzentakata, one of
the worst hit, a concrete channel funneled the tsunami surge, increasing its speed, height and destructive power.
“Construction like that makes things more dangerous,” he said.
(转自The New York Times (free registration))