従来、大きな災厄の危険性を予測して人心をあおるのは、決まって占い師や、まゆつばものの宗教者や予言者の類と相場が決まっていたが、３．１１以降は、地震学者が、迫りくる列島の危機についてさまざまな予測をするようになった。
どのような予測が出ても、ベストミックスなどという美名のもと、国は当面は原発再稼働を推進するという政策に変更を加える気はまったくないようだし、東京の首都機能移転について真剣に考えることもまったくないようである。
この危機管理意識の低さはいったい何なのか。「来たるべき将来のために設備投資を行い、危機に備える」などといった無駄は一切省き、できるだけ現状維持のまま、稼げるうちに稼げるだけ稼いでさっさと自分たちの懐に入れてしまえば、あとは野となれ山となれということなのだろうか。
何かというと、外国との比較で自らの方向性を定めるという自主性のない政策決定をしてきたのが日本という国である。アメリカやフランスが原発を何基持っているからとか、アジアの新興国が原発を増産させるからというような理由で、どうして日本がそれに盲従しなければならないのか。
国土の小さな地震大国という認識があまりに薄い。地震や津波などで、崩壊する前に処分場を決め、全原発の廃炉作業を１日でも早く進めることこそが、この国の危機管理上、今もっとも急がれなければならないことである。原発をグラウンドゼロにしないためにも。
できもしない原子力制御の研究などに無駄な税金を投入している余力があれば、１日でも早く全炉廃炉にし、エネルギー不足に耐えながら、専門家が一丸となって、この小国に一番見合った安全で新しいエネルギー供給の方途を真剣に模索することこそが、真のイノベーションにつながるのではないのか。
http://blogs.wsj.com/japanrealtime/2012/02/15/could-fukushima-daiichi-be-ground-zero-for-the-next-big-one/
Could Fukushima Daiichi Be Ground Zero for the Next Big One?
By Yoree Koh
The heft from last year’s powerful March 11 earthquake shocked a sleeping fault line close to the Fukushima Daiichi nuclear plant back to life, according to a new scientific study. And based on their findings, the scientists who conducted the study warn the battered nuclear power plant should brace itself for another big one.
- Reuters
- The Fukushima Daiichi nuclear power plant in November 2011.
The new study from the European Geosciences Union, published on Tuesday, cautions that the seismic risk at the Fukushima Daiichi nuclear plant has increased because the magnitude 9 earthquake jolted the plates underneath the area into a more precarious position. But that’s not all: The real problem may be the fluids forming as a result of the Pacific plate digging under the adjacent Okhotsk plate. Japan’s northern region lies directly above the Okhotsk plate.
According to the scientists, the fluids threaten to swim up toward fault zones, where they can soak into the brittle crust of the earth along the fault line, reducing friction, pulling the fault lines apart and triggering another large earthquake.
While the epicenter of the March 11 quake occurred about 100 miles away from the Fukushima Daiichi plant, the scientists say the next big earth-shaker could be centered much closer. The scientists concluded it would be wise to strengthen the plant’s infrastructure accordingly. The report did not predict when the earthquake will hit, except to say it would be in the “near future.”
The team of geophysicists behind the study – all based at Tohoku University in Sendai City in northeastern Japan — analyzed a sample of over 6,000 earthquakes that occurred from June 2002 to October 2011, in the northeast region. With this data, they used seismic tomography to create a detailed portrait of the area that mapped out subterranean activity. The technique is similar to the way a CT or CAT scan can uncover tumors inside humans, the scientists explain.
The team focused on the strongest aftershock following the March 11 earthquake that was centered inland. That magnitude 7 temblor hit exactly a month after the March 11 quake, underneath Iwaki, a city located just 25 miles from the troubled plant.
“There are a few active faults in the nuclear power plant area, and our results show the existence of similar structural anomalies under both the Iwaki and the Fukushima Daiichi areas. Given that a large earthquake occurred in Iwaki not long ago, we think it is possible for a similarly strong earthquake to happen in Fukushima,” said team-leader Dapeng Zhao, a geophysics professor at Tohoku University, in a statement released Tuesday.
The big aftershock in Iwaki was caused by fluids ascending from the Pacific plate to the crust, said the scientists. The fluids are a product of the Pacific plate’s shifting beneath Japan’s northeast region. The plate’s movement raises the temperature and pressure of minerals inside it, causing them to dehydrate. The fluids released are then able to move around the thick rocks toward the upper crust. Mr. Zhao and his team believe that if enough of these fluids accumulate, they could push fault zones apart, raising the risk for serious seismic activity. The rocks below where the 1995 Kobe earthquake occurred underwent a similar process, the report says.
Iwaki has such a fault zone, which had been largely dormant until stresses from the March 11 earthquake jerked it back to life, the report said. According to the report, Japan’s seismic network recorded over 24,000 tremors around Iwaki, in the seven and a half months following March 11. That number is far higher than the 1,300 quakes detected in the same area in the nine years before then.
What is more, the paper concludes, the Fukushima Daiichi plant sits on top of crust displaying the same traits as the crust under Iwaki. The paper notes that the seismicity near the plant is relatively low compared to that near Iwaki, but says the ascending fluids can still be a threat. A fault line that runs close to the plant could be weakened by these fluids.
The paper’s parting words: “Therefore, much attention should be paid to the FNPP (Fukushima nuclear power plant) seismic safety in the near future.”
Comments (5 of 5)
ボロボロ福島原発に直下型地震の危険―間近の断層に不気味な水溜まり
3・11直後の震度6「井戸沢余震」に酷似
東電「大丈夫」と対策とらず
福島原発で直下型地震の恐れ＝「耐震強化必要」―東北大教授ら
研究成果は欧州の専門誌「Solid Earth」に14日、掲載された。
趙教授らは、福島県いわき市で2011年4月11日に起きた地震（震度6弱）を引き起こした井戸沢断層と福島第1原発のすぐ近くにある双葉断層の構造を調べ、「両者の地下構造がよく似ている」（趙教授）ことを突き止めた。
二つの断層の地表から地下150キロを比較したところ、それぞれの断層の下で水が見つかった。太平洋プレートに含まれていた水が、地下の圧力で上昇したと考えられるという。井戸沢断層ではこの水が断層に入り込み、滑ったことで地震が起きたとみられ、趙教授は「双葉断層付近の水がさらに上昇して断層に入ることがないか監視すべきだ」と指摘する。