Text 4The U.S. government has recently helped people learn more about the dangers of earth

Text 4

The U.S. government has recently helped people learn more about the dangers of earthquakes by publishing a map. This map shows the chances of an earthquake in each part of the country. The areas of the map where government is spending a great deal of money and is working hard to help discover the answer to these two questions:

1. Can we predict earthquakes?

2. Can we control earthquakes?

To answer the first question, scientists are looking very closely at the most active fault systems in the country, such as the San Andreas fault in California. A fault is a break between two sections of the earth's surface. These breaks between sections are the places where earthquakes occur.

Scientists look at the faults for changes which might show that an earthquake was about to occur. But it will probably be many years before we can predict earthquakes accurately and the control of earthquakes is even farther away.

Nevertheless, there have been some interesting developments in the field of controlling earthquakes. The most interesting development concerns the Rocky Mountain Arsenal earthquakes. Here water was pat into a layer of rocks 4,000 metres below the surface of the ground. Shortly after this injection of water, there was a small number of earthquakes. Scientists have decided that the water which was injected into the rocks worked like oil on each other. When the water" oiled" the fault, the fault became slippery and the energy of an earthquake was released.

Scientists are still experimenting at the site of these earthquakes. They have realized that there is a connection between the injection of the water and the earthquake activity. They have suggested that it might be possible to use this knowledge to prevent very big, destructive earthquakes, that is, scientists Could inject some kind of fluid like water into faults and change one big earthquake into a number of small, harmless earthquakes.

36. Earthquake belts are ______.

A) maps that show where earthquakes are likely to occur

B) zones with a high probability of earthquakes

C) breaks between two sections of the earth's surface

D) the two layers of earth along a fault