SNBT EXERCISE XII9

Earthquake is any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks. Seismic waves are produced when some form of energy stored in Earth’s crust is suddenly released, usually when masses of rock straining against one another suddenly fracture and “slip.” Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another. The major fault lines of the world are located at the fringes of the huge tectonic plates that make up Earth’s crust.

Little was understood about earthquakes until the emergence of seismology at the beginning of the 20th century. Seismology, which involves the scientific study of all aspects of earthquakes, has yielded answers to such long-standing questions as why and how earthquakes occur. About 50,000 earthquakes large enough to be noticed without the aid of instruments occur annually over the entire Earth. Of these, approximately 100 are of sufficient size to produce substantial damage if their centers are near areas of habitation. Very great earthquakes occur on average about once per year. Over the centuries they have been responsible for millions of deaths and an incalculable amount of damage to property.

1. What can you conclude about the relationship between the number of earthquakes and the level of destruction they cause?

• A. Most earthquakes that occur are highly destructive.

• B. Only a very small fraction of earthquakes cause major damage.

• C. Every earthquake produces substantial damage regardless of location.

• D. Earthquakes are only dangerous when they happen far from habitation.

• E. The frequency of destructive earthquakes is equal to the total number of earthquakes.

Earthquake is any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks. Seismic waves are produced when some form of energy stored in Earth’s crust is suddenly released, usually when masses of rock straining against one another suddenly fracture and “slip.” Earthquakes occur most often along geologic faults, narrow zones where rock masses move in relation to one another. The major fault lines of the world are located at the fringes of the huge tectonic plates that make up Earth’s crust.

Little was understood about earthquakes until the emergence of seismology at the beginning of the 20th century. Seismology, which involves the scientific study of all aspects of earthquakes, has yielded answers to such long-standing questions as why and how earthquakes occur. About 50,000 earthquakes large enough to be noticed without the aid of instruments occur annually over the entire Earth. Of these, approximately 100 are of sufficient size to produce substantial damage if their centers are near areas of habitation. Very great earthquakes occur on average about once per year. Over the centuries they have been responsible for millions of deaths and an incalculable amount of damage to property.

2. According to the passage, which of the following statements about earthquakes are correct? (Choose 3)

• A. They usually occur along narrow zones called geologic faults.

• B. They are most often found at the edges of tectonic plates.

• C. They can only be studied properly since the 21st century.

• D. About 50,000 earthquakes strong enough to be noticed happen every year worldwide.

• E. Very great earthquakes occur about once every ten years.

3. Which words could best replace “incalculable” in the passage without changing the meaning? (Choose 3)

• A. countless

• B. Immeasurable

• C. Infinite

• D. Predictable

• E. Uncertain

4. Which sentence is included in the relative defining clause?

• A. Earthquake is any sudden shaking of the ground that is caused by the passage of seismic waves through Earth’s rocks.

• B. Seismic waves, which carry energy through Earth’s rocks, can cause buildings to shake.

• C. Very great earthquakes occur on average once per year.

• D. Little was understood about earthquakes until the emergence of seismology at the beginning of the 20th century.

5. Identify the noun clause in this sentence:

What scientists discovered about earthquakes helps save lives.

• A. about earthquakes

• B. helps save lives

• C. What scientists discovered

• D. discovered about earthquakes