Portals into the heart of the earth they burn.
巖漿在通往地心的入口燃燒著。
Bottomless cauldrons fueled by an ancient wrath bubbling and boiling thousands of miles beneath the surface and just waiting to burst through.
由遠古熔巖所點燃的無底大鍋，在地表下幾千英里的地方沸騰著，只待爆發(fā)。
Volcanoes are scattered across the planet.
火山遍布全球。
About 1500 active volcanoes can be found across the world though countless others are on the ocean floor.
世界各地大約有1500座活火山，但還有無數(shù)活火山位于海底。
Most volcanoes whether on land or underwater are located where tectonic plates meet.
無論是在陸地上還是在水下，大多數(shù)火山都位于地殼板塊交匯的地方。
In fact, the Ring of Fire, a path that traces the boundaries between several tectonic plates around the Pacific Ocean, contains about 75 percent of the planet's volcanoes.
事實上，這條火山帶，即環(huán)繞太平洋周圍幾個構造板塊邊界的帶狀區(qū)域，涵蓋了地球上大約75%的火山。
There are several types of volcanoes primarily classified by shape and size.
火山主要根據(jù)形狀和大小分為幾種類型。
Major types include stratovolcanoes which often appear as tall steep mountains, shield volcanoes which are flatter and dome-shaped, calderas which are large depressions in the ground and mid-ocean ridges which are underwater chains of volcanic mountains.
主要類型有：層狀火山，通?？雌饋硐穸盖偷母呱?；盾狀火山，平坦呈圓頂狀；火山口，地面上的大洼地；大洋中脊，海底的火山山脈。
No matter their shape or size, all volcanoes emit gas and molten rock.
無論它們的形狀、大小如何，所有火山都會釋放氣體和噴發(fā)熔巖。
The journey of these emissions begins deep underground in the earth's core.
這些排放物來自于地核深處。
The core, which can burn as hot as the surface of the Sun, transfers its heat to the surrounding rocky mantle.
地核的燃燒溫度與太陽表面相當，它將熱量傳遞給周圍的巖石地幔。
In doing so, the heat melts some of the rock.
在這個過程中，熱量熔化了一些巖石。
This molten rock or magma is lighter than the surrounding solid rock layer, so it rises through the mantle.
這些熔化的巖石或巖漿，比周圍的固體巖層輕，所以它穿過地幔上升。
The magma then escapes through vents in the earth's crust causing volcanic eruptions.
然后巖漿就從地殼的噴口流出，導致火山爆發(fā)。
Now above ground this magma is referred to as lava and it can reach temperatures of over 2000 degrees Fahrenheit.
在地面上，這種巖漿就被稱為熔巖，它的溫度可以達到華氏2000度以上。
In addition to lava, volcanoes may erupt with searing hot gas formed in the mantle, in a phenomenon called pyroclastic flow.
除了熔巖，火山噴發(fā)時還伴有在地幔中形成的灼熱氣體，這種現(xiàn)象叫做火山碎屑流。
This gas combined with hot ash can race down the sides of a volcano as fast as 100 miles per hour burning everything in its path.
這種氣體和灼熱的火山灰結合在一起，可以以每小時100英里的速度沿著火山的邊緣向下侵襲，燃燒沿途的一切。
To measure and classify eruptions, scientists develop the volcanic explosivity index or VEI. It considers various factors, such as the volume of lava gas and other emissions from the volcano along with the height of the eruption cloud above the volcano summit.
為了對火山爆發(fā)的強烈程度進行度量和分類，科學家們制定了火山爆發(fā)指數(shù)（VEI）。該指數(shù)考慮了各種因素，比如熔巖氣體的體積和火山的其他排放物，以及火山頂部噴發(fā)云的高度。
The VEI scale begins at zero.
VEI等級從0開始。
Each successive measurement increases logarithmically, meaning that each magnitude is 10 times more powerful than the one before it.
每一次連續(xù)的測量都呈對數(shù)增加，這意味著每一次測量的強度都是前一次測量的10倍。
The VEI scale does not have an upper limit.
VEI等級沒有上限。
But the most catastrophic eruptions measured thus far are categorized as VEI 8.
但迄今為止測量到的最具災難性的火山爆發(fā)被歸為VEI 8級。
These eruptions occurred thousands and millions of years ago.
這些爆發(fā)發(fā)生于數(shù)千年前。
The most destructive volcanic eruption ever witnessed occurred in Indonesia in 1815.
1815年，印度尼西亞遭遇了有史以來最具破壞性的火山噴發(fā)。
Mount Tambora, a large stratovolcano erupted with a VEI measurement of 7.
一座巨大的層狀火山，坦博拉火山爆發(fā)了，VEI等級為7級。
The blast caused earthquakes, tsunamis and pyroclastic flows that decimated the land and took tens of thousands of Indonesian lives.
火山爆發(fā)引發(fā)了地震、海嘯和火山碎屑流，摧毀了這片土地，奪走了數(shù)萬印度尼西亞人的生命。
The eruption even destroyed the top of Mount Tambora itself, turning the 13,000-foot-tall mountain into a 3,640-foot-deep caldera.
這次爆發(fā)甚至摧毀了坦博拉火山的頂部，將13000英尺高的山峰變成了3640英尺深的火山口。
While volcanoes are some of the most destructive forces of nature, they have also helped make life on earth possible.
雖然火山是自然界最具破壞力的力量之一，但它們也使地球有生命存在的可能。
Volcanic ash provides nutrients to nearby soil, making the land fertile.
火山灰為附近的土壤提供養(yǎng)分，使土地肥沃。
And lava when it cools hardens into rock and creates new landforms. With heat from the heart of the earth, volcanoes have helped terraform the planet, making it the rich dynamic landscape we see today.
熔巖冷卻后會硬化為巖石，形成新的地貌。憑借來自地球中心的能量，火山使地球變得適合人類居住，并成就了我們今日所見的豐富動態(tài)景觀。
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