Earthquakes are divided into two categories: natural earthquakes and artificial earthquakes. Natural earthquakes are mainly tectonic earthquakes, it is due to the deep underground rock rupture, wrong movement of the long-term accumulation of energy released sharply, in the form of seismic waves propagated out of the ground caused by the house shaking the ground. Tectonic earthquakes account for more than 90% of all earthquakes. Earthquakes caused by volcanic eruptions, called volcanic earthquakes, account for about 7% of all earthquakes. In addition, earthquakes can also be generated under certain special circumstances, such as the collapse of caverns (trapped earthquakes) and the impact of large meteorites on the ground (meteorite impact earthquakes).
Artificial earthquakes are earthquakes caused by man-made activities. Such as industrial blasting, underground nuclear explosions caused by vibration; in deep wells for high-pressure water injection as well as large reservoirs of water storage increases the pressure of the earth's crust, and sometimes induces earthquakes. (
1. What is the internal structure of the earth?
A: The interior of the Earth can be divided into three circles: the crust, the mantle, and the core.
2. What is an earthquake?
Answer: The vibration of the Earth's surface caused by the sudden release of energy slowly accumulated inside the Earth or by human factors is called an earthquake.
3. What is the source of an earthquake?
A: The place inside the earth where earthquakes occur.
4. What is meant by epicenter? What is meant by epicenter distance?
A: The point on the ground where the source of an earthquake is projected is called the epicenter. The distance from the epicenter to any point on the ground is called the epicenter distance.
5. What is the depth of epicenter? What are shallow, deep and moderate earthquakes?
Answer: The vertical distance from the epicenter to the source of the earthquake is called the depth of the epicenter.
Shallow earthquakes have an epicenter depth of 70 kilometers or less, deep earthquakes have an epicenter depth of more than 300 kilometers, and earthquakes with an epicenter depth of 70-300 kilometers are considered to be medium earthquakes.
6. How deep is the deepest earthquake in the world? How many deep earthquakes are there in those places?
Answer: The June 9, 1934, earthquake on the east of Indonesia's Sulasi Island had a depth of 720 kilometers
Deep-source earthquakes are most common in the deep trench region of the Pacific Rim, with deep-source earthquakes in northeastern China, and medium-deep-source earthquakes in the waters east of Taiwan.
7. How many types of earthquakes can be classified according to their causes?
Natural earthquakes and artificial earthquakes.
Natural earthquakes include tectonic earthquakes, volcanic earthquakes, and collapse earthquakes. Artificial earthquakes include vibrations caused by underground nuclear explosions, and earthquakes caused by water storage in reservoirs.
8. What are tectonic earthquakes? What are the characteristics of tectonic earthquakes?
Tectonic earthquakes are natural earthquakes caused by tectonic movements within the earth that result in the rupture of rock strata, which are closely related to the geological tectonic system and are mostly distributed in the earth's crust 5-30 kilometers below the ground. They are characterized by long duration, wide range of impact, strong destructive force and repetitive nature. Tectonic earthquakes account for more than 90% of earthquakes worldwide.
9. What are volcanic earthquakes?
Natural earthquakes caused by volcanic eruptions, volcanic earthquakes are short-lived, have a small area of influence, and the depth of the epicenter does not exceed 10 kilometers.
10.What is a trapped earthquake?
Earthquakes formed when the roofs of underground caverns formed by natural causes cannot support the heavy pressure of the rock layers and collapse.
11. What are local, near and far earthquakes?
Earthquakes with epicenters within 100 kilometers of each other are called local, those with epicenters between 100 and 1,000 kilometers are called near earthquakes, and those with epicenters more than 1,000 kilometers away are called distant earthquakes.
12. On the scale of magnitude, what are felt earthquakes, destructive earthquakes, large earthquakes, and micro-earthquakes?
Micro-earthquakes with a magnitude of less than 3 are called micro-earthquakes, earthquakes with a magnitude of more than 3 are called felt earthquakes, earthquakes with a magnitude of more than 5 are called destructive earthquakes, and earthquakes with a magnitude of more than 7 are called major earthquakes.
13. What is the magnitude of an earthquake?
The magnitude of an earthquake is the magnitude of the earthquake itself, which is related to the amount of energy released by the source of the earthquake, the greater the energy, the greater the magnitude of the earthquake, and there is only one magnitude for an earthquake. An earthquake has only one magnitude. A magnitude difference of one degree results in a 33-fold difference in energy.
14. What is seismic intensity? What are the factors that affect the intensity of an earthquake?
The degree of impact and damage caused by an earthquake on an area is called intensity. Generally speaking, the greater the magnitude, the greater the intensity. The same earthquake, the epicenter of the distance between the different intensity is not the same, the factors affecting the intensity, in addition to the magnitude, the epicenter of the distance, but also with the address of the structure, the ground building seismic performance and other factors.
15. What are the criteria for determining the intensity of earthquakes in China?
16. What are seismic waves?
Seismic waves are elastic waves generated inside the earth during earthquakes, and are the way earthquakes release energy.
17.What are the types of seismic waves? What are the characteristics?
Seismic waves have body waves and surface waves, body waves are divided into longitudinal waves and transverse waves
Transverse waves vibration direction perpendicular to the direction of the wave, on the ground for the left and right shaking, longitudinal waves vibration direction and the direction of propagation is the same, the ground reflects the up and down bouncing (upside down, bumps) vibration. Compared with the two, the speed of longitudinal wave propagation is faster than that of transverse wave, so the general feeling of up and down bouncing after an earthquake, followed by left and right shaking. In addition, the amplitude of transverse waves is larger than that of longitudinal waves, and the destructive force is greater. The horizontal shaking force of transverse waves is the main cause of building damage.
18. What is the difference between the meaning of magnitude and intensity?
The magnitude reflects the size of the earthquake itself, which is only related to the amount of capacity released by the earthquake, while the intensity reflects the degree of impact and damage to the ground. An earthquake has only one magnitude, while the intensity varies from place to place. The intensity is not only related to the magnitude, but also to the depth of the epicenter, the distance from the epicenter, and the conditions of the medium through which the waves pass.
19. How many earthquakes occur on Earth in a year and how many are destructive?
There are more than five million earthquakes per year worldwide, of which more than 1,000 are destructive earthquakes and more than a dozen are earthquakes of magnitude seven or higher.
20.What parts of the world have more earthquakes?
The world's earthquakes are mainly concentrated in the following two belts:
(1) the Pacific Rim Seismic Belt: including the Pacific coast of North and South America and the Aleutian Islands, Kamchatka Peninsula, through the Thousand Islands, the Japanese archipelago south of our country through Taiwan and then to the Philippines to the southeast, up to New Zealand.
(2) Himalayan - Mediterranean seismic zone: from western Indonesia through Myanmar to China's Hengduan Mountains, the Himalayas, across the Pamir Plateau, through Central Asia to the Mediterranean Sea and its coasts.
21. How deep do seismic zones originate?
Most earthquakes in the world originate 5 to 30 kilometers underground.
22. What was the world's largest earthquake?
The largest earthquake recorded so far has not exceeded the magnitude of 8.9, May 22, 1960 in Chile, South America, the magnitude of 8.9 earthquake, South America, Ecuador, South America, January 31, 1906, ---- Columbian border near the offshore and March 2, 1933, Japan, Sanriku, east of the sea, there was also a magnitude of 8.9 earthquake.
23. How many times has China had a large earthquake of magnitude 8 or more, try to give three examples
China is a country with many earthquakes, according to the available information statistics occurred more than 8 magnitude earthquake 17 times, in September 1679 occurred in Hebei Province, Sanhe, a magnitude of 8 earthquake; in December 1920 occurred in the Haiyuan of the 8.5 magnitude of the earthquake; in May 1927 occurred in Gansu Province, Gulang of the magnitude 8 earthquake; an 8.5-magnitude earthquake that occurred in August 1950 in Chashu, Tibet; and an 8-magnitude earthquake that occurred in January 1972 in the sea to the east of Taiwan.
24. How many earthquakes of magnitude 7 or above have occurred in our province? Give four examples
***Five have occurred. 8-magnitude earthquakes in Sanhe in 1679; 7.5-magnitude earthquakes in Maguxian in 1830; 7.2-magnitude earthquakes in Xingtai in 1966; 7.8-magnitude earthquakes in Tangshan in 1976; and 7.1-magnitude earthquakes in Luanxian in 1976. The earthquake was a 7.1-magnitude earthquake in Luanxian County in 1976.
25. What are the major earthquake zones in China?
China's major seismic zone in the east of the Tancheng - Lujiang seismic zone, the Hebei Plain seismic zone, Fenwei seismic zone, Yanshan - Bohai seismic zone, the southeast coastal seismic zone, etc.; the west of the northern Tianshan seismic zone, the southern Tianshan seismic zone, Qilianshan seismic zone, Kunlun Mountain seismic zone and the Himalayas seismic zone; the central part of the north-south seismic zone, running through China; and the other there is the Taiwan seismic zone, which is part of the Western Pacific seismic zone. part of the Western Pacific Seismic Belt.
26. What are the seismic belts in North China?
Earthquake zone is more earthquakes and more intense zone, the earthquake zone in North China, Hebei Plain seismic zone, Fenwei seismic zone, Yanshan - Bohai seismic zone, Lujiang seismic zone. According to the viewpoint of geomechanics, China can be roughly divided into 20 earthquake zones.
1. Taiwan Belt; 2. Fujian-Guangdong Coastal Belt; 3. Northeast Deep Earthquake Belt; 4. Yingkou-Tancheng-Lujiang Belt; 5. Hebei Plain Belt; 6. Haiyuan-Songpan-Ya'an Belt; 7. Shanxi Belt; 8. Weihe River Plain Belt; 9. Yinchuan Belt; 10. Lanzhou-Tianshui Belt; 11. Hexi Corridor Belt; 12. Mabian-Qiaoyia-Tonghai Belt; 13. Coronation-Xichang-Fishoushoushoushoushoushoushoushoushoushoushoushoushoushoushoushou; 14. Tengchong-Lancang Belt; 15. Mourning Mountains Belt; 16. Fuho-Qianning Belt; 17. Huashixia Belt; 18. Lhasa-Chashu Belt; 19. Western Tibet Belt; 20. Tianshan Belt.
27. Who invented the world's first seismograph? Briefly summarize the development of seismographs?
The world's first seismograph was invented in 132 BC by Zhang Heng, a Chinese scientist, and was called the Houfeng Geodetic Instrument.
Modern seismometers in the 18th century 90's only made, its principle and Hou Feng geodesic basically similar to the development of seismometers very quickly, a wide variety of existing long, short cycle and other types, and has realized the wireless telemetry, tape recording, digitalization and so on. Sensitivity from the magnification of a few times to thousands of times, ten thousand times, one hundred thousand times and even millions of times, the cycle range from 0.05 seconds to 100 seconds.
28. What is earthquake forecasting? How many types are there?
Earthquake forecasting is the prediction of the time, location and magnitude of future destructive earthquakes and their effects, the forecast is divided into long-term forecasts, medium-term forecasts, short-term forecasts and earthquake forecasts.
29. What is the content of long-term earthquake forecasting?
Long-term seismic forecasting refers to the prediction of seismic hazard and its effects over a period of several years to decades or longer. It includes national or regional seismic zoning; seismic intensity of construction planning and engineering sites, seismic ground motion parameters, seismic microzonation and seismic hazard prediction; and national or regional seismic activity trend prediction.
30.What are medium-term, short-term and near-shock forecasts of earthquakes?
Medium-term earthquake forecasting refers to the forecast of the time, location and magnitude of destructive earthquakes that will occur within a few months to a few years;
Short-term earthquake forecasting refers to the forecast of the time, location and magnitude of destructive earthquakes that will occur within a few days to a few months;
An imminent earthquake forecast refers to the forecast of destructive earthquakes that will occur within a few days or an alert;
31. Which earthquakes have been successfully forecast in China?
We have successfully forecast two earthquakes in Wuqia County, Xinjiang, on March 23 and 24, 1971; the 7.3-magnitude earthquake in Haicheng, Liaoning, on February 4, 1975; the 7.5-magnitude earthquakes in Longling and Luxi, Yunnan, on May 29, 1976; and the 7.3-magnitude earthquakes in Songpan and Pingwu, Sichuan, on August 16, 1976; especially the 7.3-magnitude earthquakes in Haicheng and Pingwu, Sichuan, on August 16, 1976; and the 7.3-magnitude earthquakes in Songpan and Pingwu, Sichuan. Especially Haicheng 7.3 magnitude earthquake, recognized around the world, won the second prize of the national scientific and technological progress. 1995 July 12, Yunnan Meng Lian 7.3 magnitude earthquake, the Yunnan Provincial Bureau of Seismology July 11 to the local and county cadres will report, and asked the local government to take measures to greatly reduce the damage, by the Yunnan Provincial Government and the State Seismological Bureau of the commendation.
32. At what level of leadership are the regulations on earthquake forecasting in China approved, when were they approved, and when were they issued by the State Seismological Bureau?
Approved by the State Council on June 7, 1988, and released on August 9, 1988, by the State Seismological Bureau.
33. What is the significance of the regulations on earthquake forecasting in China?
In order to strengthen the management of earthquake forecasting, to ensure the safety of people's lives and property and the smooth progress of the country's economic construction.
35. Do earthquakes have precursors?
Yes. Rock body under the action of geostress, in the process of gradual accumulation of stress and strain, strengthened, will cause the source of the earthquake and the nearby material to occur in a series of physical, chemical, biological, and meteorological anomalous changes. We call these abnormal phenomena associated with the breeding and occurrence of earthquakes as earthquake precursors. Since the 1966 Xingtai earthquake, China has recorded 1,000 precursor anomalies before 70 earthquakes of moderate to strong intensity or more.
36. How many types of earthquake precursor anomalies are there?
These can be grouped into 10 categories, namely: seismological precursors, crustal deformation, gravity, geomagnetism, geoelectricity, hydrogeochemistry, dynamics of subsurface fluids (water vapor, gas, and oil), stress, strain, meteorological anomalies, and macroscopic precursor anomalies.
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