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Where do earthquakes strike?

观看大卫·汤普森（David Thompson）博士解释了世界上地震的发生及其原因。

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So whether you’ve experienced an earthquake or not, I hope we’ve got you thinking about the size of earthquakes and where they occur. If you’ve never felt an earthquake, don’t worry. I’m a seismologist, and I’ve looked at probably tens of thousands of earthquakes on my computer, but I’ve only ever felt one really, really small one. And actually, the fact that you’ve not experienced an earthquake can tell us something important about where they strike. For many people, the most distinctive feature of earthquakes is where they occur in the world. You’ll notice that they tend to strike in very specific areas, and there are large parts of the Earth that experience few or even no earthquakes at all.

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Now, I’m based in Cardiff in the UK, which is a long way from any of these actively seismic regions. That’s why I’ve only ever felt one small earthquake. But I’m sure some of you live much closer to one of these regions, and have probably felt some significant earthquakes. The reason why earthquakes occur in some parts of the world and not others is down to one very important concept. And that is plate tectonics. Plate tectonics is the theory that the Earth’s surface is made up of a series of rigid blocks or plates.

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Now, these blocks collide at so-called plate boundaries, and it’s here where the Earth’s crust folds, breaks, crumples, and slides against each other, creating changes to our Earth such as the formation of the largest mountain ranges or the deepest sea trenches beneath the oceans. At some of these plate boundaries, the plates are colliding head-on, which is why they experience some of the largest, most powerful earthquakes. One such boundary is the Ring of Fire at the edge of the Pacific Ocean. It’s so-called because, as well as experiencing earthquakes, it’s where some of the most explosive volcanic eruptions occur. Large earthquakes can also strike at boundaries where plates move against each other side by side.

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一个例子是美国加利福尼亚州的圣安德烈亚斯断层。因此，这种类型的板移动发生了数百英里。该地区经历了许多大而巨大的地震。地震是一种危险和破坏性的力量，对全球城市构成了严重威胁。除了它们对人类生活的明显危害外，它们还有可能引起其他灾难性事件，例如我们在本课程中考虑的洪水或洪水和海啸。地震还给我们带来了一个有趣的矛盾，因为我们知道它们是危险的，但是知之甚少的是他们在维持地球的可居住性中所扮演的关键作用。

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在课程的早期，我们谈到了消耗并释放到大气中的二氧化碳的周期，以及如何调节我们的气候。好吧，板块构造，因此地震，在此过程中起着至关重要的作用，因为随着构造板的移动，它们运输了实际包含碳的岩石和矿物质。当一个盘子在所谓的俯冲带下移动另一盘时，它们允许将这些材料埋在地球深处，甚至数百万年，后来才通过火山释放回大气中。因此，如您所见，地震令人着迷，并且是我们星球上一些最极端事件的原因。

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在接下来的几个步骤中，我们将通过研究历史上最重要的地震来继续探索。我们将考虑什么构成了最大的地震，巨型地震，我们将展望未来，并考虑如何应对地震带来的持续风险。

In this video, Dr David Thompson explains where earthquakes occur in the world and the reasons for this.

在第1周，我们研究了地球的分化或内部分层。顶层是气氛我们走在上面的薄顶实层被称为crust。

一个横截面，显示了内芯，外芯，地幔，地壳和大气的地面层 A cross-section of the Earth

Plate tectonics

外壳由刚性部分组成，称为构造板。板以不同的速度和不同的方向不断地在地幔（地球中部）上移动。

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此内容取自
Cardiff University online course,

Extreme Geological Events

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There are七个主要盘子on Earth and earthquakes typically occur at the boundaries where plates meet. There are different types of boundaries characterised by how plates interact at them.

世界地图显示了七个主要的构造板的位置，以及它们在板边界处彼此朝着什么方向移动。欧亚板块覆盖欧洲和亚洲的大部分地区。澳大利亚板块覆盖了澳大利亚大陆，新几内亚，新西兰和印度洋的一部分。北美板块覆盖了北美，格陵兰，古巴，巴哈马，最东北亚以及冰岛和亚速尔群岛的大部分地区。太平洋板是一个位于太平洋下方的海洋构造板。南美板块覆盖了南美洲的大陆以及大西洋海床的一个地区。非洲板块横跨，包括非洲大陆的大部分地区。南极板覆盖了南极洲大陆。印度板块覆盖了印度次大陆的大部分以及中国和西部印度尼西亚的部分地区 Plate tectonics retrieved fromUSGS，公共区域。

Plate boundaries

There are three types of boundaries; divergent, convergent and transform boundaries and it is here where earthquakes often occur.

一张桌子显示在发散板边界如何分开板。在收敛的板块边界处，板彼此朝向撞击时，撞击了地壳。在变换板边界上，板彼此水平滑动 Three main Tectonic Plates boundary types retrieved from圣人的年龄

发散板边界

These boundaries occur along spreading centres where plates are moving apart and new crust is created by magma pushing up from the mantle.

描绘了两条巨型输送带，彼此面对，但在将新形成的海洋壳从山脊冠上移出时，朝相反的方向缓慢移动。

收敛板边界

At these boundaries, plates are moving towards one another destroying Earth’s crust as they collide.

At some of these boundaries one plate sinks under the other as they collide and the area where the plate sinks is referred to as asubduction zone。

在其他边界，板板正面碰撞，另一个板都在另一个边界上碰撞，两者都被迫向上形成山脉。

变换板边界

在这些边界，两个板彼此水平滑动。

概括

As we discovered in Week 1, the movement of plates at Earth’s crust is a unique process on our planet. It drives change and causes some of the extreme events we experience. This movement is key to understanding why earthquakes occur.