Earthquakes are the shaking, rolling or sudden shock of the earth’s surface. Earthquakes happen along "fault lines" in the earth’s crust. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted -- although scientists are working on it!
Most of the time, you will notice an earthquake by the gentle shaking of the ground. You may notice hanging plants swaying or objects wobbling on shelves. Sometimes you may hear a low rumbling noise or feel a sharp jolt. A survivor of the 1906 earthquake in San Francisco said the sensation was like riding a bicycle down a long flight of stairs.
The intensity of an earthquake can be measured. One measurement is called the Richter scale. Earthquakes below 4.0 on the Richter scale usually do not cause damage, and earthquakes below 2.0 usually can’t be felt. Earthquakes over 5.0 on the scale can cause damage. A magnitude 6.0 earthquake is considered strong and a magnitude 7.0 is a major earthquake. The Northridge Earthquake, which hit Southern California in 1994, was magnitude 6.7.
Earthquakes are sometimes called temblors, quakes, shakers or seismic activity. The most important thing to remember during an earthquake is to DROP, COVER and HOLD ON. So remember to DROP to the floor and get under something for COVER and HOLD ON during the shaking.
45. Which statement about earthquakes is not correct?
A. Earthquakes are the result of the sudden shock of the earth’s surface.
B. Earthquakes usually can be felt because they can last for a long time.
C. There are usually some signs for people to notice an earthquake.
D. People can feel an earthquake over 6.0 because it is very strong.
46. According to the passage, when the earthquake happened, a survivor of the 1906 earthquake in San Francisco_______.
A. was riding a bicycle B. was just climbing the stairs
C. heard a low rumbling noise D. felt like riding a bicycle
47. What can be inferred from the passage?
A. Most of the time, people can not feel or predict the earthquakes.
B. Earthquakes are sometimes called temblors, quakes shakers or seismic activity.
C. The Northridge Earthquake in Southern California in 1994 caused severe damage.
D. When an earthquake happens, it is important to drop on the floor immediately.