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Earthquakes

An earthquake is one of the most terrifying phenomena that nature can dish up. We generally think of the ground we stand on as "rock-solid" and completely stable. An earthquake can shatter (粉碎) that perception instantly, and often with extreme violence.
Up until relatively recently, scientists only had unsubstantiated (无确实证据的) guesses as to what actually caused earthquakes. Even today there is still a certain amount of mystery surrounding them, but scientists have a much clearer understanding.
There has been enormous progress in the past century: Scientists have identified the forces that cause earthquakes, and developed technology that can tell us an earthquake’s magnitude and origin. The next hurdle is to find a way of predicting earthquakes, so they don’t catch people by surprise.
In this article, we’ll find out what causes earthquakes, and we’ll also find out why they can have such a devastating eff
A. An earthquake is the most terrifying phenomena that nature can present to human beings.
B. An earthquake can shatter our world instantly, and often with extreme violence.
C. An earthquake is a vibration that travels through the earth’s core.
D. An earthquake is a vibration that travels through the earth’s crust.