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15 Dangerous Beauty
第十五章 美麗而危險
In the 1960s, while studying the volcanic history of Yellowstone National Park, Bob Christiansen of the United States Geological Survey became puzzled about something that, oddly, had not troubled anyone before: he couldn't find the park's volcano. It had been known for a long time that Yellowstone was volcanic in nature—that's what accounted for all its geysers and other steamy features—and the one thing about volcanoes is that they are generally pretty conspicuous. But Christiansen couldn't find the Yellowstone volcano anywhere. In particular what he couldn't find was a structure known as a caldera.
20世紀(jì)60年代，美國地質(zhì)勘測局的鮑勃·克里斯琴森在研究黃石國家公園火山史的時候，對一件事感到迷惑不解：他找不到這個公園的火山。而且，說來也怪，以前竟然沒有人為這件事費過神。很久以來，大家已經(jīng)知道，黃石公園是火山形成的——因此有那么多噴泉和其他散發(fā)蒸汽的地貌?；鹕接袀€特點，即：一般來說比較明顯。但是，克里斯琴森哪里也找不到黃石公園的火山，他尤其找不到一種名叫破火山口的結(jié)構(gòu)。
Most of us, when we think of volcanoes, think of the classic cone shapes of a Fuji or Kilimanjaro, which are created when erupting magma accumulates in a symmetrical mound. These can form remarkably quickly. In 1943, at Paricutin in Mexico, a farmer was startled to see smoke rising from a patch on his land. In one week he was the bemused owner of a cone five hundred feet high. Within two years it had topped out at almost fourteen hundred feet and was more than half a mile across. Altogether there are some ten thousand of these intrusively visible volcanoes on Earth, all but a few hundred of them extinct. But there is a second, less celebrated type of volcano that doesn't involve mountain building.
一提到火山，大多數(shù)人馬上會聯(lián)想到富士山或乞力馬扎羅山那樣典型的火山錐。那是由噴出的巖漿堆積而成的一個對稱的小山岡?；鹕藉F形成的速度可能相當(dāng)快。1943年，墨西哥帕里庫廷的一個農(nóng)夫吃驚地看到自己的一塊地里冒起了煙。一個星期以后，他做夢似的已經(jīng)成了一個152米高的火山錐的主人。不到兩年，它的高度達(dá)到了430米，直徑800多米。地球上總共有大約1萬座這種一目了然的火山，其中只有幾百座是活火山。但是，還有一種不大有名、并不造山的火山。
