美《國家地理》:科學家1年前就發出地震預警

5月12日四川省北川縣發生的致命地震之前的約10個月，一項科學報告就已經警告中國地區將面臨一次大型地震。

科學家們通過仔細研究衛星圖像，且對四川省的地殼斷層的十年來的深度和活動研究之後，發出了以上警告。

在2007年7月中期的《地殼》雜誌中，中國，歐洲和美國的科學家們寫道："斷層的長度已經足以引發一次強烈的撼動地面的地震，它的潛力將成為爆發區域性地震的來源。

科學家的結論是，地殼撞擊的能量在北川聚積，並將以地震的形式釋放出來。

現在看來這個預言精確的甚至讓人不寒而慄，當研究人員將活動的斷層在北川的彩色地圖上標示了出來時，那裡正好這場地震的震中。

來自田納西的孟菲斯大學的地震研究和信息中心的Micheal Ellis，同時也是這項研究的聯合作者之一，表示"據我所知，這是對這些活躍斷層的唯一調查。"

發生於5月12日的7.9級地震幾乎將四川省的部分地區夷為平地。中國官方今天估測死亡人數將到達5萬人，幾乎5百萬人將無家可歸。

鎖進了雜誌

可以確信中國官方對2007年7月的報告完全沒有察覺，否則事情絕不會淪為現在的局面。

"我們已經明確的標示出了這些活躍斷層的潛力，"Ellis說到。"但這個信息事實上被鎖進了一份學術期刊。"Ellis希望能用防震建築替換如今已經塌陷的建築，這樣起碼可以避免未來的悲劇。

"（地震前）我曾經去過這些小型村鎮"，Ellis說，"大多數房屋都沒有使用加固材料，而且那些地區幾乎沒有制磚廠。"

他補充說，"製造防震建築成本相對較高，但四川省的絕大多數人民卻十分貧困。"

地震背後的科學 北川的地震活動並不罕見。

"我們的證據顯示從12000至13000年前開始，北川就始終伴隨著使地表斷裂的地震。"Ellis和同事在去年夏天的報告中寫到。

在接受國家地理新聞的採訪時，Ellis說到,"根本上說，（2008年）地震的原因是印度和亞洲地殼板塊持續且不可阻擋的碰撞，其速率約為一年20-22毫米。"

此次碰撞起始於5千萬年前，當時印度下方板塊撞向了歐洲板塊。

Ellis補充說"喜馬拉雅和青藏高原便是從這個碰撞中產生的。"

隨著印度板塊持續緩慢的撞向亞洲，猛烈的時候就產生了地震，整個青藏高原都被向北推動。

"這次地震是西藏的山區向東邊成都平原移動"，一位沒有參與2007年7月報告的地質學家，科羅拉多大學的Roger Bilham說到。

問題不侷限於四川 看中國網站 禁止建立鏡像網站 。

報告的聯合作者Ellis說，隨著西藏高原北移，"西藏的中部地區正在塌陷，就像乳酪剛從烤箱中拿出來放到冷空氣中一樣。"

Ellis指出，西藏的南部邊緣在斷層一側，其面對的地震威脅和四川一樣大。

Ellis補充說:"喜馬拉雅地區相關的財產和生命損失的風險非常之大，因為有大量的人口居住在哪裡或者馬上遷移過去。"

"這風險幾乎和四川一樣高，因為人口和，類似於印度尼泊爾的，相對劣質的建築標準。"

而且，隨著印度板塊持續撞向西藏，"它正在製造新的斷層"，同時也意味著新的危險。


本文來自於美國的國家地理雜誌National Geographic
原文地址：

http://news.nationalgeographic.com/news/2008/05/080516-earthquake-predicted.html

Study Warned of China Quake Risk Nearly a Year Ago

Kevin Holden Platt in Beijing
for National Geographic News
May 16, 2008

Just ten months before a deadly earthquake struck Sichuan Province's Beichuan county on May 12, a scientific study warned that the Chinese region was ripe for a major quake.

After examining satellite images and conducting on-the-ground inspections of deep, active faults in Sichuan Province for more than a decade, scientists issued a warning.

China earthquake predicted (map)

"The faults are sufficiently long to sustain a strong ground-shaking earthquake, making them potentially serious sources of regional seismic hazard," the Chinese, European, and U.S. geoscientists wrote in the mid-July 2007 edition of the journal Tectonics.

They concluded that clashing tectonic forces were growing in Beichuan, ready to burst in an explosion of seismic energy.

With precision and what now seems like eerie foresight, the researchers charted the active faults on multicolored maps of Beichuan, which turned out to be the epicenter of the recent earthquake.

"As far as I know, this is the only investigation of these active faults," said study co-author Michael Ellis of the Center for Earthquake Research and Information at the University of Memphis in Tennessee.

(Related: "China Quake Delivered Seismic One-Two Punch" [May 15, 2008].)

The magnitude 7.9 quake that struck on May 12 almost entirely leveled parts of Sichuan Province. Chinese officials today estimated that the death toll would reach 50,000 and that nearly five million people are homeless.

(See photos of the earthquake's destruction.)

"Locked in a Journal"

There is little reason to believe Chinese officials were aware of the July 2007 report, or that it would have made much difference if they had been.

"We had certainly identified the potential of these active faults," Ellis said. "But that information was effectively locked in an academic journal."

Ellis hopes that replacing the collapsed buildings with earthquake-proof structures could prevent future tragedies.

"I've been to these little towns [before the quake]," Ellis said. "Most of the houses are built of unreinforced masonry, and you can see little brick factories all around this area.

China earthquake predicted (map)

"It is more expensive to build earthquake-proof structures," he added. And the vast majority of people in Sichuan Province are anything but rich.

The Science Behind the Quake

Earthquake activity is nothing new in Beichuan.

"We have shown evidence for surface-rupturing earthquakes along the Beichuan fault since 12,000-13,000 years ago," Ellis and colleagues reported last summer.

Speaking with National Geographic News, Ellis said, "Ultimately, the [2008] earthquake is related to the continuing and inexorable collision of India with Asia, which is occurring at a rate of about 20 to 22 milimeters [just under an inch] per year."

This collision started more than 50 million years ago, when the tectonic plate beneath India crashed into the Eurasian plate. (Watch how the plates slammed into each other.)

"The Himalayas and all of Tibet was created by this collision," Ellis added.

As the Indian plate continues its slow-motion crash into Asia-sometimes in jerks marked by earthquakes-it is pushing the entire Tibetan Plateau northward.

"This earthquake was the Tibetan mountains moving east over the plains of Chengdu [the capital of Sichuan Province]," said Roger Bilham, a geoscientist at the University of Colorado who was not involved in the July 2007 study.

Not Just Sichuan's Problem

Study co-author Ellis said that, as the Tibetan Plateau moves northward, "the interior parts of Tibet are collapsing, rather like a soufflé taken out of the oven into cold air."

Faults along the southern, Himalayan edge of Tibet present hazards as great as those underlying the Sichuan temblor, Ellis said.

"Risk associated with the loss of collateral and lives is very high along the Himalaya, because so many people live there or immediately downstream," Ellis added.

"The risk is similarly high in Sichuan [to the east], because of the population and, like India and Nepal, the relatively poor building standards," he said.

And as India continues to pound into Tibet, "it is still creating new fault lines"-and new dangers. 看中國網站 禁止建立鏡像網站 。

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