An earthquake is a vibration that travels through the earth's crust. 地震是一种穿过地壳的震动。
As snow accumulates on a steep slope, it reaches a critical point at which the slightest vibration will send it sliding into the valley below. 当雪在陡峭的斜坡上堆积时,它会达到一个临界点,在这个临界点上,最轻微的震动就会使它滑进下面的山谷。