VOA慢速英语2022--汤加的火山爆发为何威力如此之大

Explainer: Why Tonga’s Eruption¹ Was So Big

The eruption Saturday of the Hunga Tonga Hunga Ha'apai undersea volcano lasted 10 minutes. But smoke and gas from the volcano rose over 30 kilometers into the air.

It was among the world's largest volcanic² eruptions³ in the past 30 years, said New Zealand scientist Shane Cronin. He is a volcano expert at the University of Auckland.

He and Emily Lane, a tsunami⁴ expert at New Zealand's National Institute of Water and Atmospheric⁵ Research, explained why the volcanic eruption was so big.

Why was the eruption so big?

The magma inside the volcano was under enormous pressure and had gasses trapped within it. Magma is the hot liquid rock inside volcanoes.

An opening in the rock let the gas expand, which blew open a hole for the magma to escape. The main part of the volcano is about 200 meters below the sea. When it blew up, sea water poured in and turned to steam. This added to the energy of the explosion.

A tsunami travels across the ocean

A single eruption produced a tsunami of about one meter that crossed the Pacific Ocean. It damaged boats in New Zealand and caused an oil spill and two drownings in Peru. The tsunami surprised scientists because most are caused by large, undersea earthquakes that extend across large areas. The Tonga eruption was at one small area in the ocean.

Lane said one theory is that the shock wave from the volcano, which traveled around the world twice, may have given more power to the tsunami waves.

Tonga escaped the worst damage

Scientists are also uncertain why the tsunami was not bigger or more destructive in Tonga. The Polynesian kingdom of many islands sits almost on top of the volcano.

"That's the million-dollar question," Cronin said. "Looking at the images so far, the level of devastation⁶ is less than I was fearing."

By Wednesday, officials had confirmed three deaths in Tonga. Many homes were destroyed.

Lane said that Tongans got an early warning. It came from the increased activity at the volcano the day before the eruption and from the loud noise when the blast took place. Tongans had time to get to higher ground before the tsunami hit.

Lane said undersea formations that surround the many islands may also have protected parts of Tonga.

Falling rock dust and ash

The ash that has covered Tonga is acidic, but not poisonous, Cronin said. He has been telling aid workers that people can drink from their water supplies even if some ash has fallen in.

New Zealand and other nations are trying to get water and other supplies to Tonga as quickly as possible.

Cronin said all of Tonga's soil comes from volcanic ash and the latest amount of ash will quickly wash into the ground. It will also improve the soil for planting.

No global cooling

Large volcanic eruptions can sometimes cause temporary cooling around the Earth. But the Tonga eruption released only a small amount of sulfur⁷ dioxide, which scientists have linked to cooling. Alan Robock is a scientist at Rutgers University in New Jersey⁸. He said the eruption will cause a cooling of only 0.01 degree Celsius⁹.

What will happen next?

Cronin says the volcano may have exhausted¹⁰ itself and could go quiet for the next 10 to 20 years. But it is also possible there may be additional eruptions as new magma rises up quickly. Both Cronin and Lane agree the volcano needs to be watched closely to better predict future events.

Words in This Story

eruption – n. to send out rocks, ash, and lava¹¹ in a sudden explosion

tsunami – n. a very high, large wave in the ocean that is usually caused by an earthquake under the sea and that can cause great destruction when it reaches land

devastation – n. to destroy much or most of (something) : to cause great damage or harm to (something)

exhausted – adj. to completely use up

1 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。

2 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。

3 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

4 tsunami   

n.海啸

参考例句：

• Powerful quake sparks tsunami warning in Japan.大地震触发了日本的海啸预警。
• Coastlines all around the Indian Ocean inundated by a huge tsunami.大海啸把印度洋沿岸地区都淹没了。

5 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

6 devastation   

n.毁坏；荒废；极度震惊或悲伤

参考例句：

• The bomb caused widespread devastation. 炸弹造成大面积破坏。
• There was devastation on every side. 到处都是破坏的创伤。 来自《简明英汉词典》

7 sulfur   

n.硫，硫磺（=sulphur）

参考例句：

• Sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
• Burning may produce sulfur oxides.燃烧可能会产生硫氧化物。

8 jersey   

n.运动衫

参考例句：

• He wears a cotton jersey when he plays football.他穿运动衫踢足球。
• They were dressed alike in blue jersey and knickers.他们穿着一致，都是蓝色的运动衫和灯笼短裤。

9 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

10 exhausted   

adj.极其疲惫的，精疲力尽的

参考例句：

• It was a long haul home and we arrived exhausted.搬运回家的这段路程特别长，到家时我们已筋疲力尽。
• Jenny was exhausted by the hustle of city life.珍妮被城市生活的忙乱弄得筋疲力尽。

11 lava   

n.熔岩，火山岩

参考例句：

• The lava flowed down the sides of the volcano.熔岩沿火山坡面涌流而下。
• His anger spilled out like lava.他的愤怒像火山爆发似的迸发出来。