CNN News: 火山喷发

 
More than 80 percent of the Earths surface above and below sea level is volcanic and deep below the Earth's tectonic plates are always moving. 

超过80%的地球表面以上以及海平面以下是火山活动范围，而在地球构造板块深处总是在移动。

Most volcanic activity occurs where these plates collide. Deep within the Earth it is so hot that rocks slowly melt and become magma. Because this flowing substance is lighter than the rocks around it, it rises. When some of these tectonic plates shift, the magma rises even higher. Some of the magma pushes through the cracks in the Earth's crust at vent and at fissures and reaches the surface where it is then called lava. 
 
大多数火山活动发生在板块碰撞的地方。在地球深处，温度很高，以至于岩石慢慢地融化成为岩浆。因为这种流动的物质比它周围的岩石轻，所以会上升。当这些构造板块移动时，岩浆会上升得更高。一些岩浆从火山口和裂缝处穿过地壳的裂缝，到达地表，在那里它被称为熔岩。

What kind of eruption a volcano will have depends on the properties of the magma. Thin and runny magma means gas trying to escape can do so easily. 

火山喷发的类型取决于岩浆的性质。稀薄的岩浆意味着气体很容易逃逸。

When this happens the lava will flow out of the volcano. We've seen this with Hawaii's volcanoes because the lava flows slowly people can get away quickly and it rarely results in victims. But thick and sticky magma is a different story. There's less room for gases to escape and the pressure mounts.
 
当这种情况发生时，熔岩就会从火山中流出。我们在夏威夷的火山上看到过这种情况，因为熔岩流缓慢，人们可以迅速逃离，很少有人受伤。但粘稠的岩浆则是另一回事。因为气体逸出的空间更小，压力也更大。
 
Gas gets trapped in the magma which then explodes at the surface. This is called an explosive eruption and we've seen it with Mount Etna in Sicily and Mount Saint Helens in the U.S. 
 
气体被困在岩浆中，然后发生地表爆炸，这被称为爆发性喷发，我们在西西里岛的埃特纳火山和美国的圣海伦斯火山都见过。

Explosive volcanic eruptions can be dangerous and deadly. Lava, ash, debris can destroy everything in their path. In some cases, these eruptions have buried entire communities like Mount Vesuvius in Pompeii and Mount Pelee in Martinique. About 500 volcanoes have erupted since we started keeping records.
 
爆炸性的火山喷发可能是危险致命的。熔岩、火山灰和碎片会摧毁所经之处一切事物。在某些情况下，这些火山爆发掩埋了整个社区，比如庞贝的维苏威火山和马提尼克的佩利火山。自从我们开始记录以来，大约有500座火山爆发。
 
Many around the "Ring of Fire", an area from New Zealand to the coast of South America where there are the most subduction zones and plate movements. All volcanic activity is closely monitored by scientists around the world. By tracking active volcanoes, experts can see the warning signs and alert the public before an eruption. 
 
在“火圈”周围，从新西兰到南美洲海岸，是俯冲带和板块运动最多的地区。全世界的科学家都在密切监视着所有的火山活动。通过追踪活火山，专家们可以看到火山爆发前的警告信号并向公众发出警报。