The devastating earthquake that struck Japan in 2011 may have unexpectedly released nearly all of the energy that had built up near the source of the resulting tsunami, new research suggests.
These findings, detailed in tomorrow’s (Feb. 8) issue of the journal Science,may help lead to a better understanding of how earthquakes and fault zones work, “and with a better understanding, we may be able to anticipate extreme events or find out where super-large earthquakes might be possible in the world,” researcher Fred Chester, a geophysicist at Texas A&M University, told OurAmazingPlanet.
The magnitude 9.0 Tohoku-Oki quakewas the most powerful earthquake to hit Japan and the fifth-most powerful quake ever recorded, generating a tsunami that killed thousands and triggered a nuclear crisis. Research revealed the seafloor moved nearly 165 feet (50 meters) during the temblor.
Earthquakes are caused by stress that builds up on faults in the Earth’s surface. Usually, earthquakes are thought to release only a portion of this stress on the fault, but thecatastrophic level of activity seen with the 2011 temblor suggested that this quake may have relieved significantly more energy in that area — a boundary region where the tectonic plates that make up Earth’s surface meet.
Wide swaths of the Pacific coastline stretching from Honshu to Shikoku may be hit by tsunami over 20 meters high if a newly feared megaquake occurs in the Nankai Trough, a Cabinet Office panel warned Saturday.
The new warning comes after the panel revised its 2003 estimate to reflect new findings from the March 2011 earthquake and tsunami that devastated the Tohoku region’s coastline last year.
The 2003 report said no areas would see tsunami higher than 20 meters. The updated report is based on the assumption that the earthquake will have a magnitude of 9.0.
Sometimes it is better to leave the TV off. This is how I have felt since Saturday, the day that Japan’s Cabinet Office chose to announce new predictions for earthquakes and tsunamis for which Japanese citizens “should make preparations.” From the shocking scale of death and devastation which the predictions intimate, however, the only “preparations” that would be practical, or even possible, would be life insurance and tombstones.
At a televised news conference, the long-haired academics on the government’s Central Disaster Management Council duly presented data and graphics (above, from the Yomiuri Shimbun) predicting a tsunami of 10 meters or higher could strike 11 prefectures, including Tokyo, and an earthquake with an intensity of 7—the highest level on the Japanese seismic scale—in the event of a “simultaneous triple quake” along the Nankai Trough. The “triple quake” refers to quakes in three sections of the trough, Tokai, Tonankai, and Nankai. The entire trough stretches from Suruga Bay along areas off Shikoku and Kyushu.
Okushiri, Japan — On the night of July 12, 1993, the remote island of Okushiri was ripped apart by a huge earthquake and tsunami that now seem an eerie harbinger of the much larger disaster that struck northeastern Japan last March. Islanders still recall with horror how a wall of frothing black water raced out of the darkness to consume entire communities, leaving almost 200 people dead.
Officials hope to glean lessons from Okushiri’s experience.
In the half decade that followed, the Japanese government rebuilt the island, erecting 35-foot concrete walls on long stretches of its coast, making it look more like a fortress than a fishing outpost. The billion dollars’ worth of construction projects included not just the hefty wave defenses but also entire neighborhoods built on higher ground and a few flourishes, like a futuristic $15 million tsunami memorial hall featuring a stained glass panel for each victim.
But today, as Japan begins a decade-long $300 billion reconstruction of the northeast coast, Okushiri has become something of a cautionary tale. Instead of restoring the island to its vibrant past, many residents now say, the $1 billion spending spree just may have helped kill its revival.
The atmosphere directly above the fault zone which produced Japan’s recent devastating earthquake heated up significantly in the days before the disaster, a study has shown.
Before the March 11 earthquake, the total electron content in a part of the upper atmosphere, called the ionosphere, increased dramatically over the earthquake’s epicentre, reaching a maximum three days before the quake struck.
It is believed that in the days before an earthquake, the stresses on geological faults in the Earth’s crust causes the release of large amounts of radon gas.
Reporting from Kesennuma, Japan— Structural engineer Kit Miyamoto was giving a speech in Japan on earthquake safety when this month’s record quake struck, giving him a front-row seat for the unfolding disaster and what steps might save lives next time.
"This disaster basically paralyzed the whole country," said Miyamoto, president of West Sacramento-based Miyamoto International, standing amid the wreckage in this battered coastal city. "We can learn a lot of lessons for California."
What worked, and what didn’t?
Although some of the lessons will take years to nail down, experts said some things stand out already. One problem, some said, was Japan’s overreliance on the massive sea walls that were favored by its politically powerful construction industry and that provided a false sense of security.
A meltdown may have occurred at at least one nuclear power reactor in Japan, the country’s chief cabinet secretary, Yukio Edano, said Sunday, adding that authorities are concerned about the possibility of another meltdown at a second reactor.
"We do believe that there is a possibility that meltdown has occurred. It is inside the reactor. We can’t see. However, we are assuming that a meltdown has occurred," he said about the No. 1 reactor at the Fukushima Daiichi nuclear facility.
"And with reactor No. 3, we are also assuming that the possibility of a meltdown as we carry out measures," Edano said.
Edano’s comments confirm an earlier report from an official with Japan’s Nuclear and Industrial Safety Agency, who said, "we see the possibility of a meltdown."
"There is a possibility, we see the possibility of a meltdown," said Toshihiro Bannai, director of the apan’s Nuclear and Industrial Safety Agency international affairs office, in a telephone interview from the agency’s headquarters in Tokyo. "At this point, we have still not confirmed that there is an actual meltdown, but there is a possibility."
Japanese officials took the extraordinary step on Saturday of flooding a crippled nuclear reactor with seawater in a last-ditch effort to avoid a nuclear meltdown, as the nation grappled simultaneously with its worst nuclear mishap and the aftermath of its largest recorded earthquake.
A radiation leak and explosion at the Fukushima Daiichi Nuclear Power Station on Saturday prompted the government to expand an evacuation order to affect 170,000 people in the plant’s vicinity. And the plant’s operator issued an emergency notice early Sunday morning that a second reactor at the same aging plant was also experiencing critical failures of its cooling system and that rising pressure there risked a new explosion.
The government said radiation emanating from the first reactor appeared to be decreasing after the blast Saturday afternoon destroyed part of the facility, and they said that they had filled it with sea water to prevent full meltdown of the nuclear fuel.