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A seismic gap is______．
A．a region where no seismic activity has ever been recorded
B．an area where no large earthquake has ever been detected
C．a deep and wide crack in a large plate
D．located at the junction of two interlocking plates in the earth，and where no seismic activity has been recorded for a long time
答案
更多“A seismic gap is______．A．a region where no seismic activity has ever been recordedB．an are”相关的问题
第1题
Earthquake
Can Scientists Predict Killer Earthquakes？
The date was November 23，1980．People near Naples，in Southern Italy，felt the earth roll and shake. Earthquake! Suddenly buildings came tumbling down. Cracks appeared in the earth．Within minutes，entire towns were destroyed．Thousands of people were dead．Thousands more were injured．
As rescuers searched through the rubble，many people must have wondered，if only the victims had known ahead of time，many lives could have been saved．
Actually，an Italian scientist did predict that such a quake would happen．In 1977 Dr．M．Caputo of the Universite Degiles Studi in Rome warned that a large quake would soon strike the east of Naples．Unfortunately，he couldn't predict the exact time and date of the quake．
Dr．Caputo made his general prediction after talking with scientists at 54 earthquake-monitoring stations throughout Italy．He learned that many earthquakes had recently rocked different areas around Naples．But none had occurred in one particular spot east of Naples for many years．Dr. Caputo felt that the area was long overdue for a large quake．And it was．
Earthquake Strikes in Gap
The quake occurred in a region that Dr.Caputo called a seismic gap．A seismic gap is an area in an active earthquake region where no earthquake or seismic activity has been recorded in a long time．Seismic gaps are located where two large plates in the earth have become stuck．
When the plates slide past each other，they sometimes became locked in place．A similar thing happens when you make a running leap on a sidewalk while wearing sneakers．When you 1and on both feet，the sneakers grab onto rough surface．Friction tends to hold your feet back while the rest of your body goes forward．You may end up falling flat on your face．
In the case of plates，however，the uneven surfaces between the plates cause the plates to remain locked in place for years．Huge pressure builds up behind each plate．Periodically，a shudder，or tremor，is recorded as some of this energy is released．
Finally，after about 50 years，rock in the seismic gap either suddenly breaks or moves under the great stress．This sudden release of energy sends shock waves through the rock layers above．The ground shakes，sidewalks crack，and buildings tumble．A mighty quake has struck．
Gaps Used to Predict Quakes
Many geologists have used what is called the seismic gap technique to accurately predict earthquakes．The technique was first developed by Soviet earthquake expert Dr.V.Fodotov during his studies of ancient and recent Japanese earthquakes．Dr.Fodotov was marking the location，size，and date of all known quakes in Japan when he noticed a striking pattern．
All major earthquakes were found to occur in only a few isolated spots in Japan．Each of these spots，he noted，experienced a major quake only once every 50 to 60 years．Dr.Fodotov concluded that spots that hadn't had a quake in more than 50 years were “ripe” for a quake．The Russian scientist named these locations seismic gaps．
In the past several years，geologists from other countries have found seismic gaps in other parts of the world．After making detailed studies of past quakes in these regions，the geologists were able to make an accurate prediction of when a quake would occur．
How Do Animals Know When an Earthquake Is Coming？
Scientists who try to predict earthquakes have gotten some new helpers recently-animals．
That's right，animals．Scientists have begun to catch on to what farmers have known for thousands of years．Animals often seem to know in advance that an earthquake is coming，and they show their fear by acting in strange ways．Before a Chinese quake in1975，snakes awoke from their winter sleep early only to freeze to death in the cold air．Cows broke their
A．no prediction had been made
B．no correct prediction had been made
C．no one had predicted the precise date
D．no one had cared about Dr.Caputo's prediction
第2题
The attitude of the author towards the role of parents is____
A．positive.
B．negative.
C．doubtful.
D．unclear.
第4题
A. to
B.in
C.beyond
D.Under
第8题
A.#grepseismic/usr/share/dict/words/root/wordlist
B.#grepseismic/usr/share/dict/words>/root/wordlist
C.#grepseismic/usr/share/dict/wordslist/root/wordlist
D.#grepseismic/usr/share/words/root/wordlist
第9题
Earthquakes last only a few seconds. The rolling movements are called seismic waves. The seismic waves start in one place, called the epicenter, and roll outward. A seismic wave travels around the earth is a about twenty minutes. Usually, an. earthquake is strong enough to cause damage only near its epicenter.
However, epicenters at the bottom of the ocean create huge sea waves as tall as 15 meters. These waves cross the ocean in several hours. Rushing toward land, they destroy small islands and ships in their path. When they hit land, they flood coastal areas far from the epicenter of the earthquake. In 1868, a wave reached 4.5 kilometers inland in Peru. In 1896, a wave in Japan killed 27,000 people.
After an earthquake happens, people can die from lack of food, water, and medical supplies. The amount of destruction caused by an earthquake depends on where it happens, what time it happens, and how strong it is. It also depends on types of buildings, soil conditions, and population. Of the 6000 earthquakes in the world each year, only about fifteen cause great damage and many deaths.
In 1556, an earthquake in northern China killed 830,000 people--the most in history. There was no way to measure its strength. In 1935, scientists started using the Richter Scale to measure seismic waves. A seriously destructive earthquake measures 6.5or higher on the Richter Scale.
How can scientists predict earthquakes？ Earthquakes are not just scattered anywhere but happen in certain areas, places where pieces of the earth's surface meet. This pattern causes them to shake the same places many times. For example, earthquakes often occur on the west coasts of North and South America, around the Mediterranean Sea, and along the Pacific coast of Asia.
Another way to predict earthquakes is to look for changes in the earth's surface, like a sudden drop of water level in the ground. Some people say animals can predict earthquakes. Before earthquakes, people have seen chickens sitting in trees, fish jumping out of the water, snakes leaving their holes, and other animals acting strangely.
On February 4, 1975, scientists predicted an earthquake in northeastern China and told people in the earthquake zone to leave the cities. More than a million people moved into the surrounding countryside, into safe, open fields away from buildings. That afternoon, the ground rolled and shook beneath the people's feet, In seconds, 90 percent of the buildings in the city of Haicheng were destroyed. The decision to tel1 the people to leave the cities saved 10,000 lives.
However, more than a year later, on July 28, 1976, the scientists were not so lucky. East of Beijing, Chinese scientists were discussing a possible earthquake. During their meeting, the worst earthquake in modern times hit. Estimates of deaths ranged from 250,000 to 695,000. The earthquake measured 7.9 on the Richter Scale.
Earthquakes often come together with volcanic eruptions. In late 1984, strong earthquakes began shaking the Nevado del Ruiz volcano in Colombia every day. On November 14, 1985, it erupted. A nearby river became a sea of mud that buried four towns. This disaster killed more than 2100 people,
Mexico City has frequent earthquakes. An earthquake there on September 19, 1985, measured 8.1 on the Richter Scale and killed 7000 people. Most victims died when buildings fell on them.
San Francisco, California, also has frequent earthquakes. However, newer buildings there are built to be safe in earthquakes. Therefore, when all earthquake measuring 7.1 on t
A．Y
B．N
C．NG
第10题
Earthquakes
What causes earthquakes？ The earth is formed of layers. The surface of the earth, about 100 kilometers thick, is made of large pieces. When they move against each other, an earth quake happens, A large movement causes a violent earthquake, but a small movement causes a mild one.
Earthquakes last only a few seconds. The rolling movements are called seismic (地震的) waves. The seismic waves start in one place, called the epicenter (震中) , and roll outward. A seismic wave travels around the earth in about twenty minutes. Usually, an earthquake is strong enough to cause damage only near its epicenter.
However, epicenters at the bottom of the ocean create huge sea waves as tall as 15 meters. These waves cross the ocean in several hours. Rushing toward land, they destroy small islands and ships in their path. When they hit land, they flood coastal areas far from the epicenter of the earthquake. In 1868, a wave reached 4. 5 kilometers inland in Peru. In 1896, a wave in Japan killed 27,000 people.
After an earthquake happens, people can die from lack of food, water and medical sup plies. The amount of destruction caused by an earthquake depends on where it happens, what time it happens,, and how strong it is. It also depends on types of buildings, soil conditions, and population. Of the 6,000 earthquakes in the world each year, only about fifteen cause great damage and many deaths.
In 1556, an earthquake in northern China killed 830,000 people--the most in history. There was' no way to measure its strength. In 1935, scientists started using the Richter Scale to measure seismic waves. A seriously destructive earthquake measures 6.5 or higher on the Richter Scale.
How can scientists predict earthquakes？ Earthquakes are not just scattered anywhere but happen in certain areas, places where pieces of the earth' s surface meet. This pattern causes them to shake the same places many times. For example, earthquakes often occur on the west coasts of North and South America, around the Mediterranean Sea, and along the Pacific coast of Asia.
Another way to predict earthquakes is to look for changes in the earth' s surface, like a sudden drop of water level in the ground. Some people say animals can predict earthquakes. Before earthquakes, people have seen chickens sitting in trees, fish jumping out of the water, snakes leaving their holes, and other animals acting strangely.
On February 4, 1975, scientists predicted an earthquake in northeastern China and told people in the earthquake zone to leave the cities. More than a million people moved into the surrounding countryside, into safe, open fields away from buildings. That afternoon, the ground rolled and shook beneath the people' s feet. In seconds, 90 percent of the buildings in the city of Haicheng were destroyed. The decision to tell the people to leave the cities saved 10,000 lives.
However, more than a year later, on July 28,1976, the scientists were not so lucky. East of Beijing, Chinese scientists were discussing a possible earthquake. During their meeting, the worst earthquake in modern times hit. Estimates of deaths ranged from 250,000 to 695,000. The earthquake measured 7.9 on the Richter Scale.
Earthquakes often come together with volcanic eruptions. In late 1984, strong earthquakes began shaking the Nevado del Ruiz volcano in the Colombia every day. On November 14,1985, it erupted. A nearby river became a sea of mud that buried four towns. This disaster killed more than 2,100 people.
Mexico City has frequent earthquakes. An earthquake there on September 19,1985, measured 8.1 on the Richter Scale and killed 8,100 people. Most victims died when buildings fell on them.
San Francisco, California, also has frequent earthquakes. However, newer buildings
A．Y
B．N
C．NG
