#12 - Extreme earthquakes 极端地震

1.An earthquake happens when the Earth's crust moves suddenly.
The crust trembles, cracks, or lurches up and down. Earthquakes can be disastrous. They make houses fall down, tear roads apart, and destroy bridges. They can also cause tsunamis.

V Earthquakes often happen when two tectonic plates slip and grind against each other. The focus is the point where the plates suddenly move. V

2.Earthquakes happen because the Earth's crust is like a jigsaw. It is made up of several huge pieces called tectonic plates. The plates fit together quite neatly, covering the Earth. However, they can squeeze and push against each other. Sometimes, this pushing makes the plates slip and move suddenly, causing an earthquake.

V Earthquakes waves travel through and across the ground in four different ways. V

Primary waves stretch then squeeze the ground.
Secondary waves shake the ground from side to side.
Raleigh waves move in ripples up and down across the surface.
Love waves travel across the surface moving the ground from side to side.

3.Earthquakes can flatten whole cities and kill thousands.
One of the deadliest earthquakes ever hit the city of Tangshan, China in 1976. Most of the city's buildings were destroyed, and at least 240,000 people died. In 2003, an earthquake destroyed the ancient city of Bam in Iran. Over 70 percent of its buildings fell down and around 30,000 people were killed.

V Damage caused by an earthquake in Kobe, Japan, 1995. It measured 7.2 on the Richter Scale and killed more than 6000 people. V

4.Scientists measure earthquakes using the Richter scale.
It records the amount of energy that an earthquake releases. The biggest quakes are not always the most dangerous - it depends on where they happen. In a big city, a quake measuring 4 or 5 on the scale could do more damage than a quake measuring 8 or 9 in the countryside.

5.There are things you can do to stay safer during an earthquake.
For example, if you are outside, you should keep away from buildings and power lines. If you are indoors, you should shelter under a strong table. Some places also have quake-proof buildings.

V As there are a lot of earthquakes in Japan, school children regularly practice what to do if an earthquake strikes. V

当地壳突然移动时，发生地震。
地壳颤抖，裂缝或上下颠簸。地震可能是灾难性的。他们使房屋倒塌，撕裂道路，破坏桥梁。他们也可能造成海啸。

V地震通常发生在两个构造板块彼此滑动和磨合时。重点是板块突然移动的点。 V

地震的发生是因为地壳像拼图一样。
它是由几块巨大的片断构成的。这些盘子整齐地组合在一起，覆盖着地球。但是，他们可以挤压和推动对方。有时，这种推动使得板块滑动并突然移动，造成地震。

V地震波以四种不同的方式穿过和穿过地面。 V

主波拉伸然后挤压地面。

二次波从一侧到另一侧摇动地面。

罗利波浪在整个表面上上下波动。

爱情波浪穿过表面，从一边到另一边移动地面。

地震可以平整整个城市，杀死数千人。
1976年中国唐山市最致命的地震之一，大部分城市的建筑被毁，至少有24万人死亡。 2003年，一场地震摧毁了伊朗古老的巴姆市。超过70％的建筑物倒塌，约有3万人遇害。

五，1995年日本神户地震造成的损失，里氏7.2级，杀死6000多人。 V

科学家使用里氏尺度测量地震。
它记录了地震释放的能量。最大的地震不总是最危险的 - 这取决于他们发生的地方。在一个大城市，规模为4或5级的地震可能比农村地区的8或9级地震造成更大的伤害。

在地震期间，您可以做些什么来保持安全。
例如，如果你在外面，你应该远离建筑物和电力线。如果你在室内，你应该在一个坚固的桌子下面。有的地方也有防震建筑。

V由于日本有很多地震，学童经常练习如果发生地震，该怎么办？ V