本篇文章共分 5 段，從預測火山爆發的主要研究機構到科學家觀測的主要數據指標，分別說明如何利用現代科技對於火山爆發的時間進行有系統的檢測與預報。

本篇考題英文原文與對應之中文翻譯整理如下。練習作答解題時若有對語意不清楚之處，請仔細查閱對照，以提升閱讀理解能力。

Predicting Volcanic Eruptions 預測火山爆發

1. 預測火山爆發的研究機構

   Volcanoes are the landforms created when molten rock, or magma, escapes from vents in the Earth's surface and then solidifies around these vents. In any given year, roughly 50 of Earth's active volcanoes erupt — usually with some warning. Before they blow, they typically shake, swell, warm up and belch a variety of gases. Scientists from the Volcano Disaster Assistance Program (VDAP) — part of the US. Geological Survey and based at the US. Geological Survey's Cascades Volcano Observatory in Vancouver, Washington — are always on call, ready when summoned to rush at a moment's notice to an awakening volcano anywhere in the world; armed with the latest in lasers, seismometers, and other monitoring devices, they can assess the volcano's potential for violence and predict when it might ignite.

   火山是當熔化的岩石，或岩漿，從地球表面的噴氣口漏出，然後在這些噴氣口周圍凝固而形成的地貌。在任何一年當中，地球上大約有 50 座活火山爆發—通常帶有一些警告。在它們爆發之前，它們通常會搖晃、膨脹、升溫並噴出各種氣體。來自火山災害援助計劃 (VDAP) 的科學家們—隸屬於美國地質調查局，總部位於美國華盛頓州溫哥華的喀斯喀特火山觀測站—隨時待命，準備在接到通知後立即趕往世界上任何地方的甦醒火山；他們配備最新的雷射、地震儀和其他監測設備，可以評估火山的潛在威力，並預測它何時可能點燃。

2. 火山監控與成效

   Geologists have enjoyed fair success in predicting individual eruptive episodes when they concentrate on a specific volcano after an eruptive phase has begun. These monitoring efforts involve carefully measuring changes in a volcano's surface temperature, watching for the slightest expansion in its slope, and keeping track of regional earthquake activity. A laboratory at the University of Washington in Seattle is staffed 24 hours a day to monitor the rumblings of Mount St. Helens. Even with the advances brought by today's technology, however, the art of volcano prediction has not been fully mastered. The US. Geological Survey missed the call on Mount St. Helens' 1980 blast despite the fact that the mountain was being watched closely by a large team of scientists armed with the latest prediction technology. It did successfully predict the eruption of Mount Pinatubo in the Philippines evacuating virtually everyone within 25 kilometers (15 miles) before the volcano's powerful blast on May 17, 1991.

   地質學家在預測個別噴發事件方面獲得了相當大的成功，當他們在噴發階段開始後專注於一個特定的火山。這些監測工作包括仔細測量火山表面溫度的變化，觀察其坡度的輕微擴張，並跟蹤區域地震活動。位於西雅圖的華盛頓大學的一個實驗室每天 24 小時都有工作人員監測聖海倫斯火山的隆隆聲。然而，即使有今天的技術帶來的進步，火山預測的技巧還沒有被完全掌握。美國地質調查局錯過了聖海倫斯火山 1980 年的爆炸，儘管事實上有一大批科學家用最新的預測技術密切關注著這座山。它確實成功地預測了菲律賓皮納圖博火山的爆發，在 1991 年 5 月 17 日火山強大的爆炸之前，幾乎疏散了 25 公里（15 英里）內的所有人。

3. 火山爆發前之溫度與氣體徵狀

   Before a volcano erupts, hot magma rises toward the surface, so any local manifestation of increasing heat may signal an impending event. Ongoing surveys can identify new surface hot springs and take the temperature of the water and steam in existing ones. If the escaping steam isn't much hotter than the boiling point of water, then surface water is probably seeping into the mountain and being heated by contact with hot subsurface rocks, and all is well for the time being. If the steam is superheated, with temperatures as high as 500°C (900°F), then it probably derives from shallow water-rich magma, a sign that an eruption may be brewing. As magma rises, the volcanic cone itself begins to heat up. The overall temperature of a volcanic cone can be monitored from an orbiting satellite equipped with infrared heat sensors to detect the slightest change in surface temperature. This high-altitude technology serves as a simultaneous early-warning system for most of Earths 600 or so active volcanoes. Impending eruptions may also be predicted by increased gas emissions from rising magmas. For this reason, volcanologists continuously monitor sulfur dioxide and carbon dioxide emissions from potentially active volcanoes.

   在火山爆發之前，熱岩漿向地表上升，因此任何當地熱度增加的表現都可能預示即將發生的事件。持續進行的調查可以確定新的地表溫泉，並測量現有溫泉的水和蒸汽的溫度。如果逸出的蒸汽不比水的沸點高多少，那麼地表水可能是滲入山中，並透過與地下熱岩石接觸而被加熱，代表目前一切都還好。如果蒸汽是非常熱，溫度高達 500°C（900°F），那麼這蒸氣可能來自富含水分的淺層岩漿，這是一個可能正在醞釀噴發的信號。隨著岩漿的上升，火山錐體本身開始升溫。火山錐的整體溫度可以從配備紅外熱傳感器的軌道衛星上進行監測，以檢測表面溫度的最輕微變化。這種高空技術可作為地球上 600 多座活火山中大多數的同步預警系統。即將發生的火山爆發也可以透過上升岩漿的氣體排放增加來預測。由於這個原因，火山學家持續監測來自潛在的活火山的二氧化硫和二氧化碳排放。

4. 火山爆發前之地貌與震動徵狀

   Active volcanoes expand in volume as they acquire new supplies of magma from below. As a result, an increase in the steepness or bulging of a volcano's slope may signal an impending eruption. To detect the inflation of a volcanic cone, a tilt meter, a device like a carpenter's level, is used. As magma rises, it pushes aside fractured rock, enlarging the fractures as it moves. Because this type of fracturing causes earthquakes, eruptions are often preceded by a distinctive pattern of earthquake activity called harmonic tremors, a continuous rhythmic rumbling. Sensitive equipment that monitors the location where these tremors occur can measure the increased height of rising magma. The rate at which the magma rises provides an estimate of when an eruption may occur. Indeed, it served as the principal means by which scientists accurately predicted recent eruptions of Mount St. Helens.

   活火山在從下方獲得新的岩漿供應時體積會擴大。因此，火山坡度的增加或隆起可能是即將噴發的信號。為了檢測火山錐的膨脹，需要使用傾斜儀，這是一個像木匠水平儀的裝置。當岩漿上升時，它把斷裂的岩石推到一邊，隨著它的移動擴大了裂縫。由於這種類型的斷裂會引起地震，火山爆發前往往會出現一種獨特的地震活動模式，稱為諧振，即連續的有節奏的隆隆聲。監測這些震顫發生地點的高感度設備可以測量上升岩漿的高度。岩漿上升的速度提供了對可能發生噴發的時間估計。事實上，它是科學家準確預測聖海倫斯火山最近爆發的主要方法。

5. 火山爆發的不確定性

   Efforts to predict eruptions are thwarted, however, when we are unaware of a site's volcanic potential. Occasionally, a new volcano appears suddenly and rather unexpectedly, as was the case in 1943, when the volcano Paricutin developed literally overnight in the Mexican state of Michoacan, 320 kilometers (200 miles) west of Mexico City. The surrounding area was known to be volcanic because of its geologic zone, but it was not possible to predict that the volcano would appear at this particular site. Our ability to predict volcanic eruptions continues to improve but is not yet as accurate as we need it to be.

   然而，當我們不知道一個地方可能的火山潛在性時，預測噴發的努力就會受挫。偶爾，一座新的火山會突然出現，而且相當出乎意料，就像 1943 年的情況一樣，當時在墨西哥米卻肯州的帕里庫廷火山，其位於墨西哥市以西 320 公里（200 英里）處，幾乎在一夜之間出現。由於其所處的地質帶，周圍是已知的火山地區，但不可能預測火山會出現在這個特定的地點。我們預測火山爆發的能力不斷提高，但還沒有達到我們所需要的準確程度。