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This is Scientific American — 60-Second Science. I'm Julia Rosen.
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Every two weeks, on the full and new moons, the sun, moon and Earth fall along a nearly straight line. The combination of gravitational forces in this arrangement creates large swings in the tides. But the celestial alignment affects more than the oceans—it also tugs on Earth's crust, adding to the stress on faults. This makes it more likely that major earthquakes will strike at these times, according to a new study.
The idea isn't new, but scientists have had a hard time testing the earthquake-tide relationship. For instance, three of the largest earthquakes in recent years happened when tidal stress was high. But those big ones are rare and the link seems to break down for smaller events.
So the researchers crunched a bunch of numbers: by looking at more than 10,000 medium and large earthquakes, they found that the proportion of large events increased when tidal stress was high.
The results do not imply that every full or new moon will bring an earthquake—obviously. What the findings mean is that high tidal stress during new or full moons may up the chances that an earthquake will grow bigger than it otherwise might have been.
"Even magnitude 9 earthquakes start like magnitudes 1 or 2." Satoshi Ide, the University of Tokyo seismologist who led the study. "So, at the initial stage, it's very difficult to distinguish small or large earthquakes. It starts similarly, but it grows at some probability to large scale. That probability is controlled by some other effect."
And one of those effects might be the tides. Ide points out that tides in the Earth's crust are known to cause tiny tremors along deep faults. "Earthquake faults are locked everywhere, but that kind of slow deformation unlocks very small part of the fault...so it doesn't make large failure there, but once earthquake rupture starts...it can propagate very far and become very large earthquake."
The study was published in the journal Nature Geoscience.
Ide is now doing a similar analysis on earthquakes that all happened in the same geologic setting, like subduction zones. Perhaps that research will confirm whether heavenly bodies can take smaller shakes and supersize them.
Thanks for listening for Scientific American — 60-Second Science Science. I'm Julia Rosen.
参考译文
这里是科学美国人——60秒科学。我是朱莉娅·罗森。
有一分钟时间吗？
每两周，在出现满月和新月时，太阳、月亮和地球几乎就会排成一条直线。这种引力组合会产生巨大的潮汐波动。但是，这种天象影响的不仅仅是海洋，同时还会拖动地壳，增加地壳对断层的压力。一项新研究表明，这使大地震更可能在这种时期发生。
这种想法并不新鲜，但是科学家很难测试地震与潮汐之间的关系。比如，近几年最大的三起地震发生时，潮汐应力都很高。但是，大型地震发生次数较少，所以地震和潮汐之间的联系似乎被小型地震破坏了。
所以，研究人员分析了大量的数据：通过对1万多次大中型地震的观察，他们发现当潮汐应力增高时，大型地震发生的比例也会增加。
当然，这个结果并不能表明，每一次满月或新月都会引发地震。研究结果表明的是，在出现满月或新月时，潮汐应力会增高，这会使地震级别增强的可能性增加。
“即使是9级地震，开始时也只像1、2级地震。井出哲是东京大学的地震学家，也是本次研究的负责人。他还表示：“所以，一开始很难辨别是大型地震还是小型地震。因为开始时很类似，但是，之后就可能演变成大型地震。这种可能性会受到其他因素的影响。”
其中一个影响因素可能就是潮汐。井出哲指出，地壳上发生的潮汐能引起深断裂层的微小震动。“地震的断裂层是固定的，但是这种缓慢的变形解锁了一小部分的断裂，所以，不会带来巨大的影响，但是一旦地震发生，潮汐的微小震动可能会传播很远，从而演变成大型地震。”
该研究结果发表在《自然地球科学》期刊上。
井出哲现在正在对所有同一地质环境下发生的地震进行相似性分析，比如说消减带。也许那项研究可以确定天体是否可以引发小型地震并使其增强。
谢谢大家收听科学美国人——60秒科学。我是朱莉娅·罗森。
译文为可可英语翻译，未经授权请勿转载！
重点讲解
重点讲解：
1. for instance 例如；譬如；
例句：For instance, oranges, bananas and pineapples, are all fruits from the south.
例如橘子、香蕉、菠萝等，都是南方的水果。
2. break down 破坏；消除；
例句：We should break down old conventions and think big.
我们应该打破旧框框，敢于幻想。
3. a bunch of 大量；大批；
例句：I scanned a bunch of pictures from our trip to Hawaii last summer.
我把去年夏天到夏威夷旅游的一堆照片扫了进去。
4. point out 指出，说出（事实或错误）；
例句：Let me point out some of its special features.
让我指出它的一些独特的特点。
