An earthquake is a shaking of the ground caused by the sudden breaking and shifting of large sections of Earth”s rocky outer shell. Earthquakes are among the most powerful events on earth, and their results can be terrifying. A severe earthquake may release energy 10,000 times as great as that of the first atomic bomb. Rock movements during an earthquake can make rivers change their course. Earthquakes can trigger landslides that cause great damage and loss of life. Large earthquakes beneath the ocean can create a series of huge, destructive waves called tsunamis (pronounced tsoo NAH meez) that flood coasts for many miles.
Earthquakes almost never kill people directly. Instead, many deaths and injuries in earthquakes result from falling objects and the collapse of buildings, bridges, and other structures. Fire resulting from broken gas or power lines is another major danger during a quake. Spills of hazardous chemicals are also a concern during an earthquake.
The force of an earthquake depends on how much rock breaks and how far it shifts. Powerful earthquakes can shake firm ground violently for great distances. During minor earthquakes, the vibration may be no greater than the vibration caused by a passing truck.
On average, a powerful earthquake occurs less than once every two years. At least 40 moderate earthquakes cause damage somewhere in the world each year. About 40,000 to 50,000 small earthquakes--large enough to be felt but not damaging--occur annually.
附帶翻譯:地震是震動地面由突然打破和轉移地球的岩石外殼的大部分造成。地震是在最強有力的事件之中在地球上, 並且他們的結果可能是恐怖的。一次嚴厲地震也許發布能量10,000 倍偉大象那第一原子彈。岩石運動在地震期間能做河改變他們的路線。地震可能觸發導致巨大損傷和喪生的山崩。大地震在海洋之下可能創造一系列的巨大, 破壞性的波浪叫做海嘯 那次洪水沿海許多英里。
地震幾乎從未殺害人直接。反而, 許多死亡和傷害在地震起因於下落的對象和大廈、橋樑, 和其它結構的崩潰。火起因於殘破的氣體或輸電線是其它主要危險在地震期間。危害化學製品溢出並且是關心在地震期間。
地震的力量依靠多少岩石斷裂和多遠它轉移。強有力的地震可能猛烈地震動牢固的地面為了不起的距離。在較小地震期間, 振動也許沒有大于振動由一輛通過的卡車造成。 平均, 一次強有力的地震發生較不比一次每二年。至少40 次輕度地震每年造成損傷某處在世界。大約40,000 次到50,000 次小地震-- 足夠大感覺但不損壞-- 年年發生。