專家：年全球強震或增至20次 這些地區的民衆要警惕

Scientists have warned there could be a big increase in numbers of devastating earthquakes around the world next year. They believe variations in the speed of Earth’s rotation could trigger intense seismic activity, particularly in heavily populated tropical regions.
科學家警告稱，明年，世界各地發生災難性地震的次數可能會大幅度增加。他們認爲，地球自轉速度的變化可能引發強烈的地震活動，特別是在人口稠密的熱帶地區。

Although such fluctuations in rotation are small – changing the length of the day by a millisecond – they could still be implicated in the release of vast amounts of underground energy, it is argued.
儘管地球自轉的波動幅度非常小，對一天的時間長短影響不過千分之一秒，但有科學家認爲，這一變化仍然可能引發大量地下能量釋放。

The link between Earth’s rotation and seismic activity was highlighted last month in a paper by Roger Bilham of the University of Colorado in Boulder and Rebecca Bendick of the University of Montana in Missoula presented at the annual meeting of the Geological Society of America.
美國科羅拉多大學科學家羅傑•比爾漢姆與蒙大拿大學教授瑞貝卡•本迪克10月在美國地質學會年會發表研究報告，指出了地球自轉和地震活動之間的聯繫。

“The correlation between Earth’s rotation and earthquake activity is strong and suggests there is going to be an increase in numbers of intense earthquakes next year,” Bilham told the Observer last week.
比爾漢姆上週對《觀察家報》表示：“地球自轉和地震活動之間有很強的相關性，這意味着2018年強地震的次數將會增加。”

In their study, Bilham and Bendick looked at earthquakes of magnitude 7 and greater that had occurred since 1900. They found five periods when there had been significantly higher numbers of large earthquakes compared with other times.
比爾漢姆和本迪克研究了1900年後發生的所有7級以上地震。他們發現，與其他時間相比，有五個時期的大地震次數顯著增加。

“In these periods, there were between 25 to 30 intense earthquakes a year,” said Bilham. “The rest of the time the average figure was around 15 major earthquakes a year.”
比爾漢姆稱：“在這些時期，每年發生25到30次大地震。而在其他時期，平均每年大約發生15次大地震。”

The researchers searched to find correlations between these periods of intense seismic activity and other factors and discovered that when Earth’s rotation decreased slightly it was followed by periods of increased numbers of intense earthquakes. “The rotation of the Earth does change slightly – by a millisecond a day sometimes – and that can be measured very accurately by atomic clocks,” said Bilham.
研究人員探尋了這些地震活動劇烈的時期與其他因素之間的關聯，發現當地球自轉速度稍微下降後，大地震頻次就會增加。比爾漢姆表示，“地球自轉速度變化微乎其微，有時只有每天千分之一秒的差別，但是原子鐘可以非常精確地測出這種變化。”

Bilham and Bendick found that there had been periods of around five years when Earth’s rotation slowed by such an amount several times over the past century and a half. Crucially, these periods were followed by periods when the numbers of intense earthquakes increased.
比爾漢姆和本迪克發現，在過去一個多世紀裏，曾經出現過多個爲期約五年的地球自轉減速期，每次減緩千分一秒。關鍵的是，地球自轉減速期之後，大地震次數就會增加。

“It is straightforward,” said Bilham. “The Earth is offering us a five-year heads-up on future earthquakes.”
比爾漢姆稱：“很明顯，地球向提前五年給我們發了地震預警。”

This link is particularly important because Earth’s rotation began one of its periodic slowdowns more than four years ago. “The inference is clear,” said Bilham. “Next year we should see a significant increase in numbers of severe earthquakes. We have had it easy this year. So far we have only had about six severe earthquakes. We could easily have 20 a year starting in 2018.”
這個發現尤爲重要，因爲四年多前，地球進入了一個自轉減速週期。“結論顯而易見，明年我們應該會發現大地震的次數顯著增加。今年一年還算平靜，目前爲止我們只經歷了6次強烈地震。從2018年開始，我們每年很可能會經歷20次大地震。”

Exactly why decreases in day length should be linked to earthquakes is unclear although scientists suspect that slight changes in the behavior of Earth’s core could be causing both effects.
目前，還不清楚地球白晝時間縮短爲什麼會影響地震活動，但科學家懷疑，地核行爲的微妙變化可能導致了這兩種情況。

In addition, it is difficult to predict where these extra earthquakes will occur – although Bilham said they found that most of the intense earthquakes that responded to changes in day length seemed to occur near the equator. About one billion people live in the Earth’s tropical regions.
此外，儘管比爾漢姆稱，他們發現大多數白晝長度變化導致的大地震似乎都發生在赤道附近，但很難預測這些地震的震源。大約有十億居民生活在赤道附近的熱帶地區。