【英语时差8,16】地震波如何确定地震的速度和方向-下

搜索关注在线英语听力室公众号：tingroom，领取免费英语资料大礼包。

And the direction the crystals are pointing makes a difference to the speed seismic¹ waves travel through the rock: a wave traveling parallel to the crystals–in other words, along the length of the toothpick–moves faster than a wave traveling in the other direction, across the width of the crystals. So if seismic waves going through one part of the earth always travel faster in one direction than they do in another, there’s a good chance that the rock there is moving in that direction. Based on this kind of information geologists² can construct models of what’s going on in parts of the earth no one has ever seen–models that show us the slow movement of molten rock, welling up from the earth’s core, escaping here and there through volcanoes, and slowly pushing the continents around on the earth’s surface.

分享到：