Ejercicio de Reading IELTS - The Tunguska event



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Photo credits: http://en.wikipedia.org/wiki/File:Tunguska_epicenter.jpg

Kaplan ha preparado para nuestro curso IELTS este ejercicio de Reading del IELTS.

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A. The largest impact event in recent history occurred over Tunguska in Central Siberia. At 7:17am on 30th June 1908, residents reported a bluish light streaking across the sky followed by a blinding flash and sounds similar to artillery fire. It was caused by a large asteroid entering the Earth’s atmosphere and exploding.

B.  No casualties were reported but trees were flattened over a radius of more than 2000 kilometres. The explosion registered at seismic stations across Eurasia and dust particles were recorded in the atmosphere over the U.S.A. months after the event. It is also believed that the crater became what is known today as Lake Chuka but mapping at the time in this region was sketchy so this has not been proven yet.

C. It could have been a lot worse, though. With the rotation of the Earth, if it had happened a mere five hours earlier, it would have hit St Petersberg and destroyed the city. The ensuing loss of life would have been a national tragedy on a scale which is difficult to imagine.

D. Since then, scientists using computer simulations have calculated that the asteroid was approximately 20 metres in diameter. It exploded at an altitude of between 5 and 10 kilometres above the Earth’s surface with an energy of around 5 megatons. This is equivalent to 300 nuclear bombs being detonated in the same place at the same time.

E. As an asteroid enters the Earth’s atmosphere it encounters resistance which compresses it. At a critical point, this resistance causes the rock to explode which sends a high-temperature jet of expanding gas streaming towards the surface in a fireball.

F. This has caused concern that relatively small objects hitting the atmosphere can wreak widespread damage. It is statistically proven that smaller asteroids are likely to hit the planet more frequently than larger ones. There have been calls for more efforts to be made in detecting these objects and a plan of action to be drawn up.

G. Since the turn of the century, there have been numerous airbursts over Russia, the Mediterranean and, most notably, Yukon in Canada. In 2000, an object with a diameter of 5 metres exploded in the atmosphere approximately 20 kilometres above the region’s ground level. Eye witnesses claim to have seen a flash of light accompanied by a loud bang followed by a shower of fragments. An electromagnetic pulse was given out which caused a severe but temporary loss of power.

H. An asteroid measuring just 75 metres across could destroy a city the size of Washington or London. However, the world’s cities are sparsely situated so the chances of this happening are remote. The oceans cover around two thirds of the Earth’s surface so are more likely to be hit. Nevertheless, despite statistics showing the chances to be slim, asteroids do not run to a timetable so contingency plans need to be in place.

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Reading Passage 1 has eight paragraphs A-H

Choose the correct heading for each paragraph from the list below. For headings which do not belong put X

I. The Statistics Behind Asteroid Strikes
II. The Chances of an Asteroid Strike on a City
III. The Worldwide Impact
IV. The Process of an Airburst
V. The Formation of Lake Chuka
VI. A Near Miss
VII. An Airburst in Siberia
VIII. Asteroid Strikes in the Twentieth Century
IX. An Airburst in North America
X. Scientific Data Behind the Impact
XI. The Concerns over Asteroid Strikes
XII. The Largest Recorded Impact Event
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Are the following statements True, False or Not Given?

9. Airbursts usually occur between 5 and 20 kilometres above the Earth’s surface.
10. The Tunguska Event had an energy of 5 megatons.
11. An asteroid is likely to hit a city in the future.
12. Only a few people were injured in the Tunguska Event.
13. An Airburst produces a stream of flaming gas.
14. Smaller asteroids regularly hit the Earth’s atmosphere.

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Answers:
 
I.  - X
II. - H       
III. - B     
IV. - E
V.  - X
VI. -  C
VII.  - A
VIII.  -X
IX. - G
X. -  D
XI.-  F
XII. - X
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9. Not given
10. True
11. False
12. False                
13. True
14.Not given



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