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        May 13, 2008

(CNN Student News) -- May 13, 2008 Quick Guide Worst Earthquakes - Discover where some of the strongest, recent quakes have occurred. Worst Earthquakes LLOYD: One expert tells CNN that Monday's quake in China is the largest one that this region has seen "for more than a generation." But it's not the first time this type of destructive natural disaster has hit the Asian country. Paula Hancocks looks back at some of the strongest and most destructive earthquakes in recent history. (BEGIN VIDEO CLIP) PAULA HANCOCKS, CNN REPORTER: The deadliest earthquake of the past century was in China. Tanghshan, in the northeast of the country, was hit by a 7.5-magnitude quake in 1976. It killed more than a quarter of a million people and flattened the city. The U.S. Geological Survey says unofficial estimates of the death toll were up to three times higher. Just four years ago, a massive 9.1-magnitude earthquake under the sea off the Indonesian island of Sumatra triggered the deadly Boxing Day tsunami. More than 220,000 people in fourteen different countries were killed; around 1.7 million more displaced. Many of the devastated areas are still in the process of being rebuilt. A year later, 2005, northern Pakistan suffered a 7.6-magnitude earthquake. Rescue efforts were hugely complicated by the mountainous terrain; landslides and rockfalls cut off access to parts of Kashmir for days. At least 86,000 are thought to have perished. Iran has suffered a number of earthquakes over the past century. The most catastrophic in 1990 in the western part of the country killed up to 50,000. More recently, in 2003, a lesser earthquake in the southeastern town of Bam killed 31,000. The U.S. Geological Survey says this was believed to be the biggest earthquake in the area for some 2,000 years. Paula Hancocks, CNN, London. (END VIDEO CLIP) Fast Facts CARL AZUZ, CNN STUDENT NEWS: Time for some Fast Facts! Earthquakes happen when two blocks of the earth slip past one another, releasing energy through the earth's crust. An earthquake's magnitude measures how much energy is released at the source of the quake. The epicenter is the location on the surface of the earth directly above where the earthquake starts. Many quakes are followed by aftershocks, smaller tremors that occur in the same place as the main earthquake. Promo LLOYD: To help your class understand more about earthquakes, check out our Learning Activity at CNNStudentNews.com. It challenges students to investigate why and where quakes happen, and look for patterns to examine if these tremors can be predicted.

    
　

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