英语听力文摘 English Digest 288、测量火山温度

　　Taking a Volcano’s Temperature
火山喷发（volcanic¹ eruption²）是一种奇特的地质现象，是地壳运动的一种表现形式，也是地球内部热能在地表的一种最强烈的显示。是岩浆等喷出物在短时间内从火山口向地表的释放。由于岩浆中含大量挥发分，加之上覆岩层的围压，使这些挥发分溶解在岩浆中无法溢出，当岩浆上升靠近地表时，压力减小，挥发分急剧被释放出来，于是形成火山喷发。
Most of the time, volcanoes look like other mountains: solid, serene³, capped with snow–a nice place to go camping.
Unless, of course, it happens to explode and pour molten lava⁴ all over your campsite! Wouldn’t it be nice if we could predict when a volcano was about to erupt? Scientists have recently taken a big step closer toward doing just this.

　　Let’s look inside a volcano. At the center is a reservoir of molten rock, known as magma. This magma is very hot, and under a lot of pressure. When rainwater seeps⁵ into cracks in the mountain, the magma turns it into steam and forces it out again. The magma also vents⁷ away hot gasses through these same cracks.
This is a volcano’s normal state. When gasses and steam vent⁶ from a volcano’s cracks, it’s probably not about to erupt. Sometimes, however, the top layer of magma can cool, and form a hard crust over the rest of the molten rock. When this happens, rainwater is able to collect in the cracks without evaporating, and this water captures a lot of gasses that would ordinarily vent from the magma. Scientific instruments inside the volcano’s cracks record a sudden drop in temperature, and much less volcanic gas.
This is a warning sign for an imminent⁸ eruption. That cool magmaseal allows pressure to build up inside the liquid magma, much like your thumb over the top of a shaken soda⁹ bottle will seal in the pressure. When that magmaseal gives way it’s like taking your thumb off the top of the bottle, and you don’t want to be camping on the volcano when that happens!
译文：
大多数时候，火山看起来和其他的山体没有两样：固体，平静，被积雪覆盖-露营的不错选择。
除非，当然，它突然喷发，熔浆覆盖你的营地。如果我们能够预测火山什么时候会喷发，是不是更好呢？科学家们最近在此领域的研究取得了进展。
让我们一起来看看火山的内部结构吧！中心是一个熔岩的“液态区”，叫岩浆。岩浆温度很高，并且处于一定的压力之下。当雨水渗入山缝后，岩浆将其蒸发为水蒸汽，又让它排放出来。岩浆也同样通过这些山缝散发一些热气。
这是一座火山的正常状态。当气体和蒸汽可以从火山的裂缝排放时，它可能并不会喷发。然而，有时顶层的岩浆会冷却，并在外部形成一个坚硬的壳。这时，雨水聚集在岩缝中，不能蒸发。这些雨水阻止了岩浆热气的排放。在山缝中的科学仪器记录到了温度的陡然下降，和火山气体的减少。
这是即将喷发的一个预兆。冷却的岩浆壳让内部的液体压力增大。就像把你的拇指放在被摇过的苏打水瓶口上，使其密封，增加内部压力。岩浆上部的密封壳被冲开时，就像你的拇指从苏打水瓶上拿开的时候一样，在这种情况下，你就不会想要在火山上露营了。

1 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

2 eruption   

n.火山爆发；（战争等）爆发；（疾病等）发作

参考例句：

• The temple was destroyed in the violent eruption of 1470 BC.庙宇在公元前1470年猛烈的火山爆发中摧毁了。
• The eruption of a volcano is spontaneous.火山的爆发是自发的。

3 serene   

adj. 安详的，宁静的，平静的

参考例句：

• He has entered the serene autumn of his life.他已进入了美好的中年时期。
• He didn't speak much,he just smiled with that serene smile of his.他话不多，只是脸上露出他招牌式的淡定的微笑。

4 lava   

n.熔岩，火山岩

参考例句：

• The lava flowed down the sides of the volcano.熔岩沿火山坡面涌流而下。
• His anger spilled out like lava.他的愤怒像火山爆发似的迸发出来。

5 seeps   

n.（液体）渗( seep的名词复数 )；渗透；渗出；漏出v.（液体）渗( seep的第三人称单数 )；渗透；渗出；漏出

参考例句：

• Water seeps through sand. 水渗入沙中。 来自《现代汉英综合大词典》
• Water seeps out of the wall. 水从墙里沁出。 来自《现代汉英综合大词典》

6 vent   

n.通风口，排放口；开衩；vt.表达，发泄

参考例句：

• He gave vent to his anger by swearing loudly.他高声咒骂以发泄他的愤怒。
• When the vent became plugged,the engine would stop.当通风口被堵塞时，发动机就会停转。

7 vents   

（气体、液体等进出的）孔、口( vent的名词复数 )； （鸟、鱼、爬行动物或小哺乳动物的）肛门； 大衣等的)衩口； 开衩

参考例句：

• He always vents his anger on the dog. 他总是拿狗出气。
• The Dandelion Patch is the least developed of the four active vents. “蒲公英区”在这四个活裂口中是发育最差的一个。

8 imminent   

adj.即将发生的，临近的，逼近的

参考例句：

• The black clounds show that a storm is imminent.乌云预示暴风雨即将来临。
• The country is in imminent danger.国难当头。

9 soda   

n.苏打水；汽水

参考例句：

• She doesn't enjoy drinking chocolate soda.她不喜欢喝巧克力汽水。
• I will freshen your drink with more soda and ice cubes.我给你的饮料重加一些苏打水和冰块。