[Wordly L5] 15. When the Earth Quakes - Sihyun

Sihyun.m4a

4.22MB

When the Earth Quakes

Those who have lived through an earthquake describe it as one of the worst experiences of their lives. When one strikes, often without warning, people are usually too petrified to move. The ground, which a few moments before seemed so solid, suddenly lurches beneath their feet. Pictures are shaken from the walls. If the earthquake is severe enough, the walls themselves may topple. Water and gas pipes burst, fires flare up, and lives may be lost.

 

The intensity of an earthquake is determined by a measure called the Richter scale. An earthquake measuring 4.0 is considered minor, causing little, if any, harm. One measuring 8.0 is more than one thousand times as powerful; it can do immense damage. Another measure of the destructive power of an earthquake is the number of lives lost. One of the greatest natural disasters in history was the earthquake that struck China in 1556. That earthquake killed almost a million people.

 

Earthquakes do the greatest damage in urban areas where people are heavily concentrated. Most of the deaths and injuries occur when people are inside collapsing buildings. The San Francisco earthquake of 1906 measured 8.3 and killed 450 people. In 1964, Alaska, which is more sparsely settled, also experienced an earthquake measuring 8.3; there were fewer than 200 deaths there.

 

Scientists who investigate the causes of earthquakes are called seismologists. They have learned a great deal about these frightening occurrences. We know that the earth's crust or surface is made of rock five to twenty miles thick. That crust is fractured in many places. The separate pieces, or plates, fit more or less together along the break lines, which are known as "faults. Heat from the earth's interior puts pressure on these plates, causing them to move. Sometimes they rub against each other edge to edge; at other times one plate may ride up over another. These kinds of movements cause earthquakes.

 

Areas that lie along faults in the earth's crust are especially prone to earthquakes. But quakes can occur anywhere in the world. San Francisco lies on the San Andreas Fault, where the Pacific and North American plates meet. It has had two major earthquakes in the last century. The Pacific coast regions of Central and South America, where the Naza and South American plates meet, have also suffered many earthquakes and will continue to do so.

 

Unfortunately, we still do not know enough about earthquakes to be able to predict accurately when one will occur. We do, however, make sure that today's buildings and bridges are strong enough to stand up to them.
That is one reason why the 1989 San Francisco earthquake, which measured 6.9 on the Richter scale, took so few lives. But earthquakes are still to be feared. If you should have the misfortune to get caught in one, your first thought might be to flee to the nearest open space. Experts tell us, however, that if you are in a modern building, it is probably safer to stay inside. Look for shelter under a sturdy table or in a doorway.