An earthquake is a vibration of the earth's surface caused by the sudden release of slowly accumulated energy in the earth's interior. When the energy accumulated in the movement of the earth exerts a huge pressure on the earth's crust that exceeds the limit that the rock layers can withstand, the rock layers will suddenly break or dislocate, causing the accumulated energy to be released sharply and spread in all directions in the form of seismic waves. , forming an earthquake. A strong earthquake is often followed by a series of smaller aftershocks.
Earthquakes are divided into two categories: natural earthquakes and artificial earthquakes. Natural earthquakes are mainly tectonic earthquakes. They are caused by the cracking and dislocation of rocks deep underground, which rapidly releases the energy accumulated over a long period of time and spreads out in the form of seismic waves, causing shaking and ground shaking on the ground. Tectonic earthquakes account for more than 90% of the total number of earthquakes. Followed by earthquakes caused by volcanic eruptions, called volcanic earthquakes, accounting for about 7% of the total number of earthquakes. In addition, earthquakes may also occur under certain special circumstances, such as cave collapse (collapse earthquakes), large meteorites impacting the ground (meteor impact earthquakes), etc.
Artificial earthquakes are earthquakes caused by human activities. For example, vibrations caused by industrial blasting and underground nuclear explosions; high-pressure water injection in deep wells and water storage in large reservoirs increase the pressure on the earth's crust and sometimes induce earthquakes. (
1. What is the internal structure of the earth?
Answer: The interior of the earth can be divided into three layers: crust, mantle, and core.
2. What Is it an earthquake?
Answer: The sudden release of slowly accumulated energy in the earth's interior or the vibration of the earth's surface caused by human factors is called an earthquake.
3. What is an earthquake source?
Answer: The place where an earthquake occurs inside the earth.
4. What is the epicenter?
Answer: The projection point of the earthquake source on the ground is called the epicenter. The distance to any point on the ground is called the epicenter distance.
5. What is the focal depth?
Answer: From The vertical distance from the epicenter to the earthquake source is called the focal depth.
Shallow earthquakes have a focal depth within 70 kilometers, deep earthquakes have a focal depth of more than 300 kilometers, and those with a focal depth of 70-300 kilometers are intermediate earthquakes. /p>
6. How deep is the deepest earthquake in the world? Which places have the most deep earthquakes?
Answer: The earthquake in the east of Sulasi Island, Indonesia, on June 9, 1934. , with a focal depth of 720 kilometers
The most deep earthquakes occur in the deep trench area around the Pacific Ocean. There are deep earthquakes in northeastern my country and medium-deep earthquakes in the waters east of Taiwan.
7. How many types of earthquakes can be divided into according to their causes?
Natural earthquakes include tectonic earthquakes, volcanic earthquakes, and underground earthquakes. Vibrations caused by nuclear explosions, earthquakes caused by reservoir water storage, etc.
8. What are the characteristics of tectonic earthquakes?
Tectonic earthquakes are caused by tectonic movements within the earth. The natural earthquakes caused are closely related to the geological tectonic system and are mostly distributed in the earth's crust 5-30 kilometers underground. They are characterized by long duration, wide range of influence, strong destructive power, and repetitive tectonic earthquakes. More than 90% of earthquakes.
9. What is a volcanic earthquake?
A natural earthquake caused by a volcanic eruption has a short duration, a small impact area, and a focal depth that does not exceed 10 kilometers.
10. What is a collapse earthquake?
An earthquake caused by the collapse of the underground cave roof due to natural causes.
11. What are local earthquakes, near earthquakes, and distant earthquakes?
The epicenter distance is within 100 kilometers, which is local earthquake. The epicenter distance is between 100 kilometers and 1000 kilometers, which is near earthquake. The epicenter distance is more than 1000 kilometers. Teleseismic.
12. Magnitude is a scale. What are felt earthquakes, destructive earthquakes, major earthquakes and micro-earthquakes?
Those with a magnitude less than 3 are called micro-earthquakes, and those with a magnitude above 3 are called micro earthquakes. Those with a magnitude above 5 are called destructive earthquakes, and those with a magnitude above 7 are called major earthquakes.
13. What is magnitude?
Magnitude refers to the size of the earthquake itself. It is related to the amount of energy released by the earthquake source. The greater the energy, the greater the magnitude. An earthquake has only one magnitude. The magnitude difference is one level and the energy difference is 33 times.
14. What is earthquake intensity? What are the factors that affect earthquake intensity?
The impact and degree of damage caused by an earthquake to a certain area is called intensity. Generally speaking, the greater the magnitude, the greater the intensity. The same earthquake has different intensities depending on the epicenter distance. The factors that affect the intensity, in addition to magnitude and epicenter distance, are also related to the address structure, the seismic performance of ground buildings and other factors.
15. What are the criteria for judging the intensities expressed in the China Earthquake Intensity Scale?
16. What are seismic waves?
Seismic waves are elastic waves generated inside the earth when earthquakes occur. They are the way earthquakes release energy.
17. Types of seismic waves? What are the characteristics?
Seismic waves include body waves and surface waves, and body waves are divided into longitudinal waves and transverse waves
The vibration direction of transverse waves is perpendicular to the direction of wave forward, and it appears as left and right shaking on the ground, and longitudinal wave vibrations The direction is consistent with the direction of propagation, and the vibration of up and down beating (bumps and turbulence) is reflected on the ground. Comparing the two, longitudinal waves propagate faster than transverse waves. Therefore, after an earthquake, you will generally feel jumping up and down, followed by shaking left and right. In addition, the amplitude of transverse waves is larger than that of longitudinal waves, and the destructive power is greater. The horizontal shaking force of shear waves is the main cause of building damage.
18. What are the different meanings of magnitude and intensity?
Magnitude reflects the size of the earthquake itself, which is only related to the ability of the earthquake to release, while intensity reflects the degree of impact and damage to the ground. An earthquake has only one magnitude, but the intensity varies from place to place. Intensity is not only related to the magnitude, but also related to many factors such as the depth of the earthquake source, the distance from the epicenter, and the conditions of the medium through which seismic waves pass.
19. How many earthquakes occur on the earth in a year, and how many destructive earthquakes are there?
There are more than 5 million earthquakes in the world every year, including more than 1,000 destructive earthquakes and more than a dozen major earthquakes of magnitude 7 or above.
20. Which places in the world have more earthquakes?
World earthquakes are mainly concentrated in the following two zones:
(1) Pacific Rim Seismic Zone: including the Pacific coasts of North and South America, the Aleutian Islands, Kamchatka Peninsula, and the Kuril Islands , the Japanese archipelago goes south through Taiwan, my country, then to the Philippines, turns southeast, and reaches New Zealand.
(2) Himalayas---Mediterranean seismic zone: from western Indonesia through Myanmar to the Hengduan Mountains in my country, the Himalayas, across the Pamir Plateau, through Central Asia to the Mediterranean Sea and its coast.
21. How deep do earthquake zones originate?
The epicenters of most earthquakes in the world are mostly located 5 to 30 kilometers underground.
22. Which was the largest earthquake in the world?
The largest earthquake recorded so far has not exceeded the 8.9 magnitude earthquake. The 8.9 magnitude earthquake occurred in Chile, South America on May 22, 1960, and the 8.9 magnitude earthquake in Ecuador, South America on January 31, 1906 - Columbia. An 8.9-magnitude earthquake also occurred in the offshore waters near the Asian border and on March 2, 1933, in the sea east of Sanriku, Japan.
23. How many times have earthquakes of magnitude 8 or above occurred in our country? Here are three examples.
my country is a country with many earthquakes. According to existing data, earthquakes of magnitude 8 or above have occurred. 17 times, an 8-magnitude earthquake occurred in Sanhe, Hebei Province in September 1679; an 8.5-magnitude earthquake occurred in Haiyuan in December 1920; an 8-magnitude earthquake occurred in Gulang, Gansu Province in May 1927; The 8.5-magnitude earthquake in Chayu, Tibet, and the 8-magnitude earthquake that occurred in the sea east of Taiwan in January 1972.
24. There have been several earthquakes with a magnitude of 7 or above in our province. Here are four examples.
*** There have been 5 earthquakes. An 8-magnitude earthquake occurred in Sanhe in 1679; a 7.5-magnitude earthquake occurred in Ci County in 1830; a 7.2-magnitude earthquake occurred in Xingtai in 1966; a 7.8-magnitude earthquake occurred in Tangshan in 1976; a 7.1-magnitude earthquake occurred in Luanxian County in 1976 Earthquakes.
25. What are the main seismic zones in my country?
The main seismic zones in eastern my country are the Tancheng-Lujiang seismic zone, the Hebei Plain seismic zone, the Fenwei seismic zone, and the Yanshan ---The Bohai Sea seismic zone, the southeast coastal seismic zone, etc.; in the west there are the North Tianshan seismic zone, the South Tianshan seismic zone, the Qilian Mountains seismic zone, the Kunlun Mountains seismic zone and the Himalayas seismic zone; in the middle there are the north and south seismic zones that run through China; in addition there are There is the Taiwan Seismic Belt, which is part of the Western Pacific Seismic Belt.
26. What are the earthquake zones in North China?
Seismic zones are areas where earthquakes occur more frequently and are more intense. The earthquake zones in North China include the Hebei Plain seismic zone, the Fenwei seismic zone, the Yanshan-Bohai seismic zone, and the Lujiang seismic zone. According to the perspective of geomechanics, my country can be roughly divided into 20 seismic zones.
1. Taiwan belt; 2. Fujian and Guangdong coastal belt; 3. Northeast deep earthquake zone; 4. Yingkou-Tancheng-Lujiang belt; 5. Hebei plain belt; 6. Haiyuan-Songpan-Ya'an belt; 7. Shanxi belt; 8. Weihe Plain belt; 9. Yinchuan belt; 10. Lanzhou-Tianshui belt; 11. Hexi Corridor belt; 12. Mabian-Qiaojia-Tonghai belt; 13. Mianning-Xichang-Yichuan belt ; 14. Tengchong-Lancang belt; 15. Ailao Mountain belt; 16. Luhuo-Qianning belt; 17. Huashixia belt; 18. Lhasa-Chayu belt; 19. Western Tibet belt; 20. Tianshan belt.
27. Who invented the world’s first seismograph? Briefly describe the development of seismometers?
The world's first seismograph was invented by Chinese scientist Zhang Heng in 132 BC, called the Hou Feng seismograph.
Modern seismographs were only produced in the 1890s. Their principles are basically similar to those of Hou Feng seismographs. Seismographs have developed rapidly and come in many types. There are various types such as long and short period, and Wireless telemetry, tape recording, digitization, etc. have been implemented.
The sensitivity ranges from a few times amplification to a thousand times, ten thousand times, one hundred thousand times or even one million times, and the period ranges from 0.05 seconds to 100 seconds.
28. What is earthquake prediction? How many types?
Earthquake forecasting is the prediction of the time, location, magnitude and impact of future destructive earthquakes. Forecasting is divided into long-term forecasting, medium-term forecasting, short-term forecasting and imminent earthquake forecasting.
29. What is the content of long-term earthquake forecast?
Long-term earthquake forecasting refers to the prediction of earthquake hazards and their impacts over a period of several years to decades or longer. Including national or regional earthquake zoning; construction planning and seismic intensity of engineering sites, earthquake ground motion parameters, earthquake small zoning and earthquake damage prediction; national or regional earthquake activity trend prediction.
30.What are medium-term, short-term and imminent earthquake forecasts?
Medium-term earthquake forecast refers to the prediction of the time, location and magnitude of destructive earthquakes that will occur within a few months to a few years;
Short-term earthquake forecast refers to a few days to a few months Forecast of the time, location and magnitude of a destructive earthquake that will occur within a few days;
Immediate earthquake forecast refers to the forecast or warning that a destructive earthquake will occur within a few days;
31. How many earthquakes has our country successfully predicted?
It has successfully predicted two earthquakes in Wuqia County, Xinjiang on March 23 and 24, 1971; the 7.3 magnitude earthquake in Haicheng, Liaoning on February 4, 1975; and the Yunnan earthquake on May 29, 1976. The 7.5 magnitude earthquake in Longling and Luxi, and the 7.3 magnitude earthquake in Songpan and Pingwu, Sichuan on August 16, 1976. In particular, the 7.3-magnitude earthquake in Haicheng was recognized worldwide and won the second prize of the National Science and Technology Progress Award. On July 12, 1995, a 7.3-magnitude earthquake occurred in Menglian, Yunnan. The Yunnan Provincial Seismological Bureau reported to the prefectural and county cadres meeting on July 11, and asked the local government to take measures to greatly reduce the losses. It received support from the Yunnan Provincial Government and the National Seismological Bureau. Commendation.
32. Which level of leaders approved my country’s earthquake prediction regulations, when were they approved, and when were they issued by the State Seismological Administration?
Approved by the State Council on June 7, 1988, and issued by the State Seismological Administration on August 9, 1988.
33. What is the significance of my country’s earthquake prediction regulations?
In order to strengthen the management of earthquake forecasts, ensure the safety of people's lives and property and the smooth progress of national economic construction.
35. Are there any signs of earthquakes?
Yes. Under the action of in-situ stress, the rock mass will cause a series of abnormal changes in physics, chemistry, biology, and meteorology in the earthquake source and nearby materials during the process of gradual accumulation and strengthening of stress and strain. We call these abnormal changes related to the birth and occurrence of earthquakes earthquake precursors. Since the 1966 Xingtai earthquake, my country has recorded 1,000 precursor anomalies before 70 moderately strong earthquakes or above.
36. How many types of earthquake precursor abnormalities are there?
Can be classified into 10 categories, namely: seismological precursors, crustal deformation, gravity, geomagnetism, geoelectricity, hydrogeochemistry, underground fluid (water vapor, gas, oil) dynamics, stress, strain, Meteorological anomalies and macro precursor anomalies.
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