Question

[Lê Quỳnh Anh]

* Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50.

  Most volcanoes are found along an imaginary belt, called the Ring of Fire, that encircles the Pacific Ocean. However, volcanic activity takes place in many far-flung regions of the world such as Hawaii, Iceland, Europe, and even the floor of the earth’s oceans. The leading theory as to why volcanic activity, as well as earthquakes, takes place when and where it does is called the theory of “plate tectonics”. The theory holds that the outer shell of the earth is divided into many different rigid sections of rock, called plates. These plates are not static, they are in continuous motion over a layer of partly melted rock. While their movement may appear insignificant, at only several inches per year, it is not. Indeed, the collisions between plates caused by this almost imperceptible movement can have catastrophic consequences. Volcanic activity and earthquakes are concentrated near the boundaries of these giant, moving plates.

  The majority of volcanoes are formed at te point where two plates collide. One of the plates is forced underneath the other. As the plate sinks, the earth’s heat and the friction of the movement cause a portion of the sinking plate to melt. This melted portion of plate is called magma, and when it reaches the earth’s surface it becomes a volcano. Volcanoes can also be created when two plates begin to diverge. Then, magma from below the earth’s crust moves up to fill the void between the two plates. Large quantities of lava spill out from the void. Volcanoes of this type usually are found not on land, but on the ocean floor. In extreme instances this can lead to the formation of gigantic, sunken mountain ranges like Mid-Atlantic Ridge that spans nearly the entire length of the Atlantic Ocean. The theory of plate tectonics also explains why some volcanic activity takes place so far from any known plate boundaries. Basically, these volcanoes are the result of huge column of magma, or plumes, that rise up and break through the surface of the earth.

 Which of the following is true about volcanoes formed at the point at which two plates diverged?

A. Most volcanoes are formed in this way 

B. Plate tectonic theory is not able to explain it 

C. The Mid- Atlantic Ridge is an example of this 

D. They do not involve magma

Answer 1

[Dương Hoàn Anh]

Chọn B                                 Câu đề bài: Điều nào sau đây nói đúng về núi lửa hình thành tại điểm mà tại đó hai mảng kiến tạo phân kỳ?

Đáp án C: Dãy núi trung du Đại Tây dương là một ví dụ tiêu biểu

Các đáp án còn lại:

A. Hầu hết các núi lửa hình thành theo cách này

B. Học thuyết kiến tạo mảng không thể giải thích được

D. Chúng không bao gồm đá nóng chảy

Thông tin trong bài:

Volcanoes can also be created when two plates begin to diverge. Then, magmafram below the earth’s crust moves up to fill the void between the two plates. Large quantities of lava spill out fiom the void. Volcanoes of this type usually are found not on land. but on the ocean floor. In extreme instances this can lead to the formation of gigantic, sunken mountain ranges like Mid- Atlantic Ridge that spans nearly the entire length of the Atlantic Ocean.

Núi lửa cũng có thể được tạo ra khi hai mảng kiến tạo bắt đầu phân kì. Sau đó, magma từ bên dưới lớp vỏ trái đất di chuyển lên để lấp đầy khoảng trống giữa hai mảng. Một lượng lớn dung nham tràn ra từ khoảng trống. Các loại núi lửa thuộc loại này thường không được tìm thấy trên đất liền, mà ở thềm đại dương. Trong những trường hợp cùng cực, điều này có thể dẫn đến sự hình thành các dãy núi khổng lồ, trũng như Mid-Atlantic Ridge (dãy núi trung du Đại Tây dương) trải dài gần như toàn bộ chiều dài của Đại Tây Dương.