EXPLORATIONS - Yellowstone Volcano

EXPLORATIONS - Yellowstone Volcano¹
By Paul Thompson

Broadcast: Wednesday, August 11, 2004

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VOICE ONE:

This is Faith Lapidus.

VOICE TWO:

And this is Doug Johnson with EXPLORATIONS in VOA Special English. Today we tell about Yellowstone National Park. It is one of the most beautiful national parks in the United States. However, an ancient and extremely violent volcano created the great beauty of Yellowstone. The ancient volcano that formed Yellowstone is not dead. It is only sleeping. And some experts say it could become very dangerous in the future.

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VOICE ONE:

 
Minerva Springs is a place in Yellowstone where hot water comes out of the ground leaving colorful minerals.
Yellowstone National Park is in the western state of Wyoming. It is one of the most unusual places in the world. Extremely hot water shoots out of the ground in several hundred places. Small lakes contain water that is so hot it is dangerous to come too close.

Visitors can watch bubbles² coming up through boiling, hot mud. They can see rocks that were once liquid and have cooled into strange shapes.

Yellowstone is built on an ancient volcano. A lake of hot liquid rock is about six kilometers under the park. This lake is about sixty-five kilometers wide. Experts say this lake is under huge amounts of pressure. The pressure and heat cause hot water to shoot out of the ground and mud to boil at Yellowstone.

VOICE TWO:

The Yellowstone volcano has often been called a super volcano because it is so big. Scientists believe major volcanic⁴ activity in the Yellowstone area began about two million years ago. This activity created violent explosions⁵ and built mountains and valleys. Experts believe this super volcano had three major explosions called eruptions⁷. Each of those three eruptions may have been more powerful than any in recorded history.

Each eruption⁶ threw out millions of tons of ash and rock. The last eruption was so huge it covered much of North America with ash. Some of this ash traveled high into the atmosphere and was carried by strong winds around the world.

This cloud of volcanic ash circled the Earth many times. It affected⁸ the climate by limiting the amount of sunlight that reached Earth's lower atmosphere and surface. This last eruption formed the mountains and valleys that visitors can see today in Yellowstone.

VOICE ONE:

When a volcano erupts, a huge amount of material explodes out of the volcano. This leaves a giant circular⁹ hole in the ground, called a caldera. Experts have known for many years that Yellowstone was formed by volcanic activity. However they could not find the caldera. Many experts searched a huge area in and around Yellowstone Park looking for the remains¹⁰ of the caldera. A few years ago, the National Aeronautics¹¹ and Space Agency¹² tested new satellite cameras. They offered Yellowstone Park officials photographs of the park taken from space.

VOICE TWO:

 
Yellowstone from space.
A national park expert was extremely surprised when he looked at the photographs taken from space. He immediately saw the caldera they had been searching for. The photographs showed that Yellowstone National Park is the caldera. The caldera is about seventy kilometers long and thirty kilometers wide.

In fact, the park is a system of calderas formed within the past sixteen million years. Experts now believe that as many fifteen or twenty smaller eruptions also formed calderas.

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VOICE ONE:

Scientists know the volcanic heart of Yellowstone is deep within the Earth. This area is called a hot spot. It is only one of a few such places on Earth.

Extreme pressure deep in the Earth forces liquid rock up through the hot spot to the lake of hot material that is below the surface. This causes the extreme heat that is found in Yellowstone.

Scientists also know the Yellowstone hot spot is linked to the activity of the North American plate. The North American plate is one of several plates that make up the surface of the Earth. These plates move a few centimeters each year. The hot spot does not move. Very often the action between the hot spots and the plate causes great earthquakes as plates move against each other. The plates often split¹³ apart. And often after earthquakes, the hot spot forces liquid rock to the surface. This has not happened for several thousand years.

VOICE TWO:

The Yellowstone hot spot has been linked with the North American plate for as long as seventeen million years. At many different times, the hot spot has caused a kind of liquid rock called basalt to explode to the surface.

This basalt rock from the Yellowstone hot spot can be found in the western states of Washington, Oregon, California, Nevada and Idaho. Evidence of this basalt rock can be found in an area as large as three hundred twenty-two thousand square kilometers.

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VOICE ONE:

Yellowstone National Park is the oldest national park in the world. About three million people visit it each year. Its great natural beauty has made it one of the most popular national parks.Most visitors like to see "Old Faithful¹⁴", the world's most famous geyser. A geyser shoots hot water high into the air. There are more than three hundred geysers in Yellowstone.

 
Old Faithful geyser.
Old Faithful is not the biggest or the most beautiful geyser. But it is the most popular. Visitors gather around Old Faithful before each eruption. Experts at the park are able to predict when these will happen. The average time between eruptions is about ninety minutes. Old Faithful shoots water an average of forty meters into the air. This eruption lasts between two and five minutes. Old Faithful releases¹⁵ up to about thirty thousand liters¹⁶ of water into the air each time.

VOICE TWO:

The hot spot deep under the ground produces geysers like Old Faithful. Old Faithful is evidence of the volcanic activity at Yellowstone. But will the Yellowstone volcano erupt again? Most experts think the answer is yes. But no one knows when. The most recent of the three extremely powerful eruptions was about six hundred fifty thousand years ago.

Experts say at least thirty smaller volcanic eruptions have taken place at Yellowstone. Some of these were perhaps as big as the nineteen ninety-one eruption at Mount³ Pinatubo in the Philippines. Several are believed to have been much larger. The most recent of these smaller eruptions took place about seventy thousand years ago.

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VOICE ONE:

Volcano experts say it is extremely difficult to tell when Yellowstone might become an active volcano again. However, earthquakes near a volcano are usually good evidence that a volcano might become active again. For example, Mount Saint¹⁷ Helens in the northwestern state of Washington exploded in nineteen eighty. Several earthquakes took place near the volcano before that time. On the morning that it exploded, Mount Saint Helens experienced¹⁸ an earthquake of five point one on the Richter scale.

Yellowstone National Park experiences several thousand earthquakes each year. Most are very small. They cannot be felt. They can only be measured by scientific instruments. However, in August of nineteen fifty-nine, an earthquake at Yellowstone measured seven point five on the Richter scale. Twenty-eight people were killed.

It was one of the strongest earthquakes ever recorded in the United States. But Yellowstone's sleeping giant volcano did not erupt.

VOICE TWO:

In two thousand one, the United States Geological¹⁹ Survey, Yellowstone National Park and the University of Utah signed an agreement.

That agreement established the Yellowstone Volcano Observatory²⁰. Under the agreement, the park, the Geological Survey and the university are responsible for improving efforts to study the volcanic system of Yellowstone.

The observatory uses information from many different instruments on the ground and from satellites to study the volcano. The information will help officials decided²¹ if Yellowstone's huge volcano is becoming a danger. Then they could warn the public quickly if necessary.

Experts at the observatory say Yellowstone represents some danger to the public. It always has. However, its natural beauty also makes it a treasure that could not be possible without the sleeping giant volcano that is under Yellowstone National Park.

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VOICE ONE:

This program was written by Paul Thompson. It was produced by Mario Ritter. This is Doug Johnson.

VOICE TWO:

And this is Faith Lapidus. Join us again next week for another EXPLORATIONS program in VOA Special English.

1 volcano   

n.火山

参考例句：

• The volcano unexpectedly blew up early in the morning.火山一早突然爆发了。
• It is most risky to go and examine an active volcano.去探察活火山是非常危险的。

2 bubbles   

泡( bubble的名词复数 )； 泡影； 肥皂泡； （欲表达的）一点感情

参考例句：

• Bubbles are rising from the bottom of the boiling water. 水泡从沸水的底部升到水面。
• The incorporation of air bubbles in the glass spoiled it. 玻璃含有气泡，使它质量降低。

3 mount   

n.山峰，乘用马，框，衬纸；vi.增长，骑上（马）；vt.提升，爬上，装备

参考例句：

• Their debts continued to mount up.他们的债务不断增加。
• She is the first woman who steps on the top of Mount Jolmo Lungma.她是第一个登上珠穆朗玛峰的女人。

4 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。

5 explosions   

爆炸( explosion的名词复数 )； 爆发； 激增； （感情，尤指愤怒的）突然爆发

参考例句：

• Soon afterwards five explosions were heard from the area. 此后不久从那个地方传来五次爆炸声。
• They were monitoring the upper air to collect evidence of atomic explosions. 他们正在检测高空空气以收集原子爆炸的证据。

6 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。

7 eruptions   

n.喷发，爆发( eruption的名词复数 )

参考例句：

• There have been several volcanic eruptions this year. 今年火山爆发了好几次。 来自《简明英汉词典》
• Over 200 people have been killed by volcanic eruptions. 火山喷发已导致200多人丧生。 来自辞典例句

8 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

9 circular   

adj.圆(形)的，环形的；循环的；n.传单，通报

参考例句：

• The bright boy altered it to a circular form.这个聪明的男孩把它改成了圆形。
• The lamp stands on a circular base.这盏台灯是装在圆形底座上的。

10 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

11 aeronautics   

n.航空术，航空学

参考例句：

• National Aeronautics and Space undertakings have made great progress.国家的航空航天事业有了很大的发展。
• He devoted every spare moment to aeronautics.他把他所有多余的时间用在航空学上。

12 agency   

n.经办；代理；代理处

参考例句：

• This disease is spread through the agency of insects.这种疾病是通过昆虫媒介传播的。
• He spoke in the person of Xinhua News Agency.他代表新华社讲话。

13 split   

n.劈开，裂片，裂口；adj.分散的；v.分离，分开，劈开

参考例句：

• Who told you that Mary and I had split up?谁告诉你玛丽和我已经离婚了？
• The teacher split the class up into six groups.老师把班级分成6个小组。

14 faithful   

adj.守信的，忠实的，如实的，可靠的

参考例句：

• They promised to be faithful to their ideal for ever.他们保证永远忠于自己的理想。
• We must be honest and faithful to the people.我们对人民必须忠诚老实。

15 releases   

v.释放( release的第三人称单数 )；放开；发布；发行

参考例句：

• Nuclear fission releases tremendous amounts of energy. 核裂变释放出巨大的能量。 来自《现代汉英综合大词典》
• Zemel says that when calcium levels are low, the body releases a hormone that helps squeeze the most out of every available milligram of the mineral. 泽莫尔博士说，当人体中的钙含量偏低时，身体里就会产生一种荷尔蒙，它能帮助肌体最大限度地吸收所摄入的钙。 来自《简明英汉词典》

16 liters   

n.升( liter的名词复数 )

参考例句：

• In the metric system, measurements are made in metres and liters. 在公制中，用米和升作计量单位。 来自《简明英汉词典》
• This can holds five liters of water. 这个容器可装五升水。 来自《简明英汉词典》

17 saint   

n.圣徒；基督教徒；vt.成为圣徒，把...视为圣徒

参考例句：

• He was made a saint.他被封为圣人。
• The saint had a lowly heart.圣人有谦诚之心。

18 experienced   

adj.有经验的；经验丰富的，熟练的

参考例句：

• Experienced seamen will advise you about sailing in this weather.有经验的海员会告诉你在这种天气下的航行情况。
• Perhaps you and I had better change over;you are more experienced.也许我们的工作还是对换一下好，你比我更有经验。

19 geological   

adj.地质（学）的

参考例句：

• aeons of geological history 数以亿万年计的地质史
• The workers skirted the edge of the cliff on a geological survey. 工人们沿着崖壁作了一次地质勘察。 来自《简明英汉词典》

20 observatory   

n.天文台，气象台，瞭望台，观测台

参考例句：

• Guy's house was close to the observatory.盖伊的房子离天文台很近。
• Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。

21 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。