Scientists have warned there could be a big increase in numbers of devastating¹ earthquakes around the world next year. They believe variations in the speed of Earth’s rotation² could trigger intense seismic³ activity, particularly in heavily populated tropical regions.

科学家警告称，明年，世界各地发生灾难性地震的次数可能会大幅度增加。他们认为，地球自转速度的变化可能引发强烈的地震活动，特别是在人口稠密的热带地区。

Although such fluctuations⁴ in rotation are small – changing the length of the day by a millisecond – they could still be implicated⁵ in the release of vast amounts of underground energy, it is argued.

尽管地球自转的波动幅度非常小，对一天的时间长短影响不过千分之一秒，但有科学家认为，这一变化仍然可能引发大量地下能量释放。

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 Boulder⁶ and Rebecca Bendick of the University of Montana in Missoula presented at the annual meeting of the Geological Society of America.

美国科罗拉多大学科学家罗杰•比尔汉姆与蒙大拿大学教授瑞贝卡•本迪克10月在美国地质学会年会发表研究报告，指出了地球自转和地震活动之间的联系。

“The correlation⁷ 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.

比尔汉姆上周对《观察家报》表示：“地球自转和地震活动之间有很强的相关性，这意味着2018年强地震的次数将会增加。”

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.

比尔汉姆和本迪克研究了1900年后发生的所有7级以上地震。他们发现，与其他时间相比，有五个时期的大地震次数显著增加。

“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.”

比尔汉姆称：“在这些时期，每年发生25到30次大地震。而在其他时期，平均每年大约发生15次大地震。”

The researchers searched to find correlations⁸ 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 accurately⁹ by atomic clocks,” said Bilham.

研究人员探寻了这些地震活动剧烈的时期与其他因素之间的关联，发现当地球自转速度稍微下降后，大地震频次就会增加。比尔汉姆表示，“地球自转速度变化微乎其微，有时只有每天千分之一秒的差别，但是原子钟可以非常精确地测出这种变化。”

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.

比尔汉姆和本迪克发现，在过去一个多世纪里，曾经出现过多个为期约五年的地球自转减速期，每次减缓千分一秒。关键的是，地球自转减速期之后，大地震次数就会增加。

“It is straightforward,” said Bilham. “The Earth is offering us a five-year heads-up on future earthquakes.”

比尔汉姆称：“很明显，地球向提前五年给我们发了地震预警。”

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.”

这个发现尤为重要，因为四年多前，地球进入了一个自转减速周期。“结论显而易见，明年我们应该会发现大地震的次数显著增加。今年一年还算平静，目前为止我们只经历了6次强烈地震。从2018年开始，我们每年很可能会经历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，还不清楚地球白昼时间缩短为什么会影响地震活动，但科学家怀疑，地核行为的微妙变化可能导致了这两种情况。

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，尽管比尔汉姆称，他们发现大多数白昼长度变化导致的大地震似乎都发生在赤道附近，但很难预测这些地震的震源。大约有十亿居民生活在赤道附近的热带地区。