地内气体与火山活动

 Like rising bubbles in champagne, gases from Earth’s interior can ascend to the surface and cause magma to explode in dangerous splatters.

 就象香槟酒中上升的气泡，地球内部的气体可以上升到地球表面，引起岩浆进行危险性的喷发。

 A new study, detailed in the July 13 issue of the journal Science, shows that these volcanic “gas slugs” originate from deeper inside the planet than previously thought.

 一项新研究表明，与原以为的情况有所不同，火山中这些“长形气泡”起源于地球内部的更深处。该研究详细地记录在不久前出版的《科学》（Science）杂志上。

 The work, by Mike Burton and colleagues at the National Institute of Geophysics and Volcanology in Italy, could help scientists understand why some volcanoes erupt more violently than others.

 这项研究工作是由意大利国家火山地理研究所的迈克·伯顿及同事所做的，有助于科学家们了解为什么有些火山比另外的火山爆发的更加猛烈。

 While the classic image of a volcanic eruption is that of explosive flares that shoot columns of lava and ash into the air, volcanoes are also capable of much milder outbursts.

 尽管典型的火山形象是突然地爆发，将熔岩柱和火山灰喷向空中，但是火山的爆发也可以轻微得多。

 Called “Strombolian” activity—after the Stromboli volcano in Italy where it has been best studied—these small volcanic blasts consist of relatively viscous lava sputtering from the throat of volcanoes, like over-cooked chili on a stove.

 这种火山的小规模爆发被叫做斯特隆布利式活动，因为意大利的斯特隆布利火山一直是研究此类活动最理想的地点。这种爆发中的熔岩相对粘稠，从火山口喷溅出来，就象用火炉过度烹饪时溢出的红辣椒。

 Strombolian eruptions are driven by pockets of water vapor and other gases ascending rapidly through lava tubes inside the Earth. The elongated bubbles, or “slugs,” can measure several tens of meters long and are formed by several smaller bubbles coalescing together as they climb toward the planet’s surface. At Stromboli, the slugs rise at a speed of about 6 feet (2 meters) per second.

 一团团的水蒸汽和其他气体沿着地球内部的熔岩管道快速上升，推动了斯特隆布利式活动的爆发。这种长形气泡长度可达几十米，在爬向地球表面的过程中，由较小气泡接合而成。在斯特隆布利火山中，气泡是以大约每秒6英尺（2米）的速度上升的。

 (“Slugs” is a scientific term used to describe a bubble with a length at least twice as long as the diameter of the tube through which it travels. It does not refer to slimy gastropods in this context.)

 “Slugs（长形气泡）”是个科学术语，用来描述具有一定长度的气泡，其长度至少是所在管道直径的两倍，在这里并不是指那种粘粘糊糊的鼻涕虫。

 Previous studies based on seismic data have suggested the slugs originate from a depth of at least 820 feet (250 meters), and possibly as much as half a mile (900 meters) beneath a volcano’s summit crater.

 以前的研究以地震资料为依据，表明长形气泡起源于至少820英尺（250米）的深处，也有可能起源于处在顶峰的火山口以下半英里（900米）的深处。

 In the new study, Burton and his team measured changes in the composition of gas escaping from Stromboli during both quiet and active periods. They measured the gas from a safe distance using a beam of infrared light that can detect chemicals in the air. The chemical composition of the gases can be used to gauge the pressure at which they formed, and thus the depth at which the slugs originated.

 在这项新研究中，伯顿和他的研究小组分别在平静期和活跃期测出了斯特隆布利火山所冒出气体的成分变化。他们在安全的距离，利用可以探明空气中化学成分的红外光束，检测了冒出的气体。气体中的化学成分可以用来测量这些气体是在多大的压力下形成的，这样就可以测量出长形气泡的起源深度了。

 The team’s findings suggest the gas slugs formed as deep as 1.7 miles (2,700 meters) below the surface.

 研究小组发现，长形气泡形成于地表以下深达1.7英里（2,700米）的深处。

 Steve Lane, a volcanologist at Lancaster University in the United Kingdom, who was not involved in the study, said the new findings are “very important” and will help scientists understand how the structure ofStromboli’s hidden plumbing system changes with depth, as well as how fluid flows within the conduits.

 英国兰开斯特大学火山学家史蒂夫·莱恩没有参与这项研究，但他表示，这些新发现非常重要，将有助于科学家们了解斯特隆布利火山隐藏的管道系统结构是如何随着深度的变化而变化的，以及管道内的液体是如何流动的。

 “These changes are often precursors of change in eruption style and provide a powerful forecasting tool,” Lane told LiveScience.

 莱恩指出：“这些变化通常预示着火山爆发方式的变化，可以作为可靠的预测手段。”