科学美国人60秒 SSS Big Earthquakes May Be More Likely During New and Full Moons
时间：2018-12-24 作者：英语课 分类：2016年Scientific American(九)月
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 1 alignment 2 affects more than the oceans—it also tugs 3 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 4 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 5 along deep faults. “Earthquake faults are locked everywhere, but that kind of slow deformation 6 unlocks very small part of the fault…so it doesn’t make large failure there, but once earthquake rupture 7 starts…it can propagate very far and become very large earthquake.”
The study was published in the journal Nature Geoscience. [Satoshi Ide, Suguru Yabe and Yoshiyuki Tanaka, Earthquake potential revealed by tidal influence on earthquake size–frequency statistics]
Ide is now doing a similar analysis on earthquakes that all happened in the same geologic 8 setting, like subduction zones. Perhaps that research will confirm whether heavenly bodies can take smaller shakes and supersize them.
—Julia Rosen
- The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
- Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。
- The church should have no political alignment.教会不应与政治结盟。
- Britain formed a close alignment with Egypt in the last century.英国在上个世纪与埃及结成了紧密的联盟。
- The raucous sirens of the tugs came in from the river. 河上传来拖轮发出的沙哑的汽笛声。 来自辞典例句
- As I near the North Tower, the wind tugs at my role. 当我接近北塔的时候，风牵动着我的平衡杆。 来自辞典例句
- Our feet crunched on the frozen snow. 我们的脚嘎吱嘎吱地踩在冻雪上。 来自《简明英汉词典》
- He closed his jaws on the bones and crunched. 他咬紧骨头，使劲地嚼。 来自英汉文学 - 热爱生命
- The story was so terrible that It'sent tremors down my spine. 这故事太可怕，它使我不寒而栗。
- The story was so terrible that it sent tremors down my spine. 这故事太可怕，它使我不寒而栗。
- The deformation frequencies are not sufficiently distinctive.其变形频率不是十分明显的。
- The calculated deformation is almost equal to the real situation by measurement.经检测，计算变形量与实际情况基本一致。