Earthquake knowledge

1. What is an earthquake?

The earthquake we often say refers to the sudden release of slowly accumulated energy in the earth, which causes the vibration of the earth's surface.

2. How many layers can the earth be divided into? Which floor often has earthquakes?

The interior of the earth can be divided into three layers: crust, mantle and core. According to statistics, about 92% of earthquakes occurred in the crust, and the rest occurred in the upper mantle.

3. How many earthquakes can occur on the earth in a year?

Earthquakes happen every day on the earth, about 5 million times a year. About 50 thousand people can feel it; Can cause injury about 1000 times; On average, there are more than a dozen major earthquakes of magnitude 7 or above every year.

4. According to the causes of earthquakes, what are the types of earthquakes?

According to the causes, it can be divided into natural earthquakes and artificial earthquakes. Natural earthquakes include tectonic earthquakes, volcanic earthquakes and subsidence earthquakes. Vibration directly caused by human factors is man-made earthquake, such as vibration caused by underground nuclear explosion. What we usually call earthquakes, mostly natural earthquakes, is a frequent natural phenomenon and a special manifestation of crustal movement.

5. According to the causes of earthquakes, what types of earthquakes have occurred in the world at present?

It mainly belongs to tectonic earthquake. According to statistics, tectonic earthquakes account for more than 90% of the total number of earthquakes in the world.

6. What are the three basic parameters of an earthquake?

Time, place and magnitude of the earthquake.

7. What is the focal point, epicenter and epicentral distance?

The place where earthquakes occur inside the earth is called the source. The projection point of the source on the ground is called the epicenter. The distance from the epicenter to any point on the ground is called epicentral distance.

8. What is the focal depth? What are shallow earthquakes, deep earthquakes and moderate earthquakes?

The distance from the epicenter to the source is called the focal depth. The earthquake with focal depth less than 70 kilometers is shallow earthquakes; Earthquakes with a focal depth of more than 300 kilometers are called deep earthquakes; Earthquakes with a focal depth of 70-300 kilometers are moderate earthquakes.

9. What are near earthquakes, near earthquakes and far earthquakes?

The epicentral distance within 100 km is called a near earthquake; The epicentral distance1000 km-1000 km is called a near earthquake; Earthquakes are those whose epicentral distance exceeds 1000 km.

10. What is the order of magnitude? What are the factors that affect the size?

Magnitude is the magnitude of the earthquake itself, which is related to the energy released by the source. The greater the energy, the greater the order of magnitude; The magnitude difference is one level and the energy difference is about 30 times.

1 1. What kinds of earthquakes can be classified according to magnitude?

According to the magnitude, earthquakes of magnitude 7 and above are called major earthquakes; Earthquakes below magnitude 7, magnitude 5 and above are called strong earthquakes or moderate earthquakes; Earthquakes below magnitude 5 and above magnitude 3 are called small earthquakes; Weak earthquakes and microseisms are earthquakes with magnitude less than 3, 1 or 1 or above. A magnitude less than 1 is called an ultrashort earthquake.

12. What is the magnitude of the largest recorded earthquake in the world?

8.9, which occurred in the Chile earthquake on May 22nd, 1960.

What is the earthquake intensity? What are the factors that affect the strength?

The degree of influence and destruction of an earthquake on a certain area is called seismic intensity, or intensity for short. Generally speaking, the greater the magnitude, the greater the intensity. The intensity of the same earthquake is high when the epicentral distance is small, but low when it is short. In addition to magnitude and epicentral distance, the factors affecting intensity are also related to focal depth, geological structure and foundation conditions.

14. What's the difference between magnitude and intensity?

Magnitude reflects the size of the earthquake itself and is only related to the energy released by the earthquake. Expressed by "quantity"; Intensity indicates the degree of influence and destruction on the ground, which is expressed by "degree". Earthquakes have only one magnitude, and their intensity varies from place to place.

15. What is the isointensity line? What is the function of isointensity line graph?

Isointensity line is the connecting line of all points with the same intensity on the ground. The contour map of equal intensity draws the general outline of earthquake impact, which provides a scientific basis for us to quickly evaluate earthquake disasters and deploy earthquake relief work.

What is an earthquake sequence? What are main shock, aftershock and foreshock? What types are earthquake sequences generally divided into?

In a certain period of time, a series of earthquakes with different sizes occurred in the same source area, and their seismogenic mechanisms have some internal relations or the same seismogenic structure, which is called earthquake sequence.

The strongest earthquake in the earthquake sequence is called the main earthquake; After the main earthquake, a smaller earthquake in the same earthquake area is called aftershock; Smaller earthquakes that occurred in the same earthquake area before the main earthquake are called foreshocks. Earthquake sequences can be divided into the following categories:

(1) Main earthquake type-The magnitude of the main earthquake is high and prominent, and the energy released by the main earthquake accounts for more than 90% of the whole earthquake sequence, which can be divided into main earthquake-aftershock type and foreshock-main earthquake-aftershock type;

(2) earthquake swarm type-there is no prominent main earthquake, and the main energy is released through several earthquakes with similar magnitude;

(3) Isolated type (single earthquake)-Its main feature is that there are almost no foreshocks and almost no aftershocks.

17. What is a destructive earthquake? Severe destructive earthquake?

Destructive earthquake refers to an earthquake event that causes certain casualties and economic losses.

Severe destructive earthquake refers to an earthquake event that causes serious casualties and economic losses, makes the disaster area lose or partially lose its self-recovery ability, and requires the state to take rescue action.

18. What is the urban "direct earthquake"? What are the most typical "direct earthquakes" in cities?

Earthquakes in big cities and their surrounding areas are called "direct earthquakes" in cities, which is a term put forward by Japanese scholars. Such earthquakes often cause great losses to cities. The most typical "direct earthquakes" in cities are 1976 Tangshan earthquake in China and 1995 Hanshin earthquake in Japan.

19. Who invented the first seismograph in the world? What year?

The first seismograph in the world (Hou Feng seismograph) was invented by Zhang Heng, a scientist in the Eastern Han Dynasty. The Longxi earthquake was recorded in 132.

20. When and where were the earliest seismic networks and seismic telemetry networks built in China?

1930, under the auspices of Li Shanbang and Qin Xinling, the first seismic station in China-Jiu Feng Seismic Station in Xishan, Beijing was established. 1966 Beijing Telemetry Network has built 8 substations. 1975 After the Haicheng earthquake, it was expanded for the first time, and 2 1 substations were distributed in Beijing, Tianjin, Tang and Zhang areas. 1980 for the second expansion and implementation of encryption project. 1990 after the Datong earthquake, the third expansion was carried out and the "North China Network Networking" project was implemented.

2 1. What's the difference between seismic shear waves and longitudinal waves?

The vibration direction of shear wave is perpendicular to the forward direction of wave, while the vibration direction of longitudinal wave is consistent with the propagation direction. In the epicentre area, seismic waves directly enter the ground, and shear waves sway from side to side, while longitudinal waves jump up and down, and the propagation speed of longitudinal waves is faster than shear waves. In addition, the amplitude of shear wave is larger than that of longitudinal wave, which is destructive, and the horizontal swing force of shear wave is the main reason for building damage.

22. What is an earthquake zone? How many major earthquake zones are there in the world?

Areas where earthquakes occur frequently and strongly are called earthquake zones. There are two main seismic zones in the world:

(1) The seismic belt around the Pacific Ocean includes the Pacific coast of North and South America, and extends from Aleutian Islands, kamchatka peninsula and Japanese Islands to Province of Taiwan Province Province in China in the south, and then turns southeast through Philippine Islands to New Zealand. The energy released accounts for 76% of the energy released by global earthquakes;

(2) Himalayan-Mediterranean seismic belt, from Indonesia via Myanmar to Hengduan Mountains and Himalayas in China, across Pamirs, via Central Asia to the Mediterranean Sea and its vicinity, released 24% of the energy released by global earthquakes.

23. Why is China a country prone to earthquakes?

According to statistics, earthquakes in Chinese mainland account for about one-third of the earthquakes in the mainland of the world. China is located between the two major earthquake zones in the world, and some areas are part of these two earthquake zones, which affects a large area.

24. Which provinces (autonomous regions) in China have more earthquakes?

The earthquake-prone provinces (regions) in China are Taiwan Province, Tibet, Xinjiang, Yunnan and Sichuan.

25. What is the "North-South Seismic Belt"?

Starting from Ningxia, China, and passing through eastern Gansu, western Sichuan and Yunnan, there is an earthquake-intensive zone running through Chinese mainland in a general north-south direction, which is called China North-South Seismic Zone. The belt can extend north to Mongolia and south to Myanmar.

Second, the knowledge of earthquake prediction

1. What is an earthquake precursor? What are the common precursors?

The anomalies related to earthquakes in nature before earthquakes are called earthquake precursors. Include microscopic precursors and macroscopic precursors. Common earthquake precursor phenomena include: abnormal change of groundwater, abnormal reaction of animals, crustal deformation, small earthquake activity, ground sound, ground light, geomagnetism, gravity change, geoelectric change, in-situ stress change, change of radon content or other chemical components in groundwater, and change of seismic wave velocity.

2. What are the abnormal changes of groundwater before the earthquake? What interference should be eliminated?

The fluctuation of groundwater level, discoloration, odor change, flowering, bubbling and sudden change of hot spring water temperature may all be earthquake precursors. However, the change of groundwater is a very complicated phenomenon, and we must pay attention to eliminating the interference of precipitation (rain and snow), drought, river fluctuation, snow melting, artificial pumping irrigation, environmental pollution and other factors.

Is it necessary to have an earthquake when the weather changes suddenly?

No, there are indeed some records of meteorological anomalies before major earthquakes, but the relationship between meteorology and earthquakes is very complicated. Even if there is a certain correlation, it is indirect and can only work under certain special conditions. For a region, weather changes often occur, but destructive earthquakes rarely occur. Some people think there will be an earthquake as soon as they see the weather change. This kind of worry is completely unnecessary.

4. Does the abnormal living habits of animals mean that there will be a big earthquake?

Not necessarily. Because there are many reasons for the abnormal living habits of animals: for example, weather changes, living conditions changes, biological interference, changes in feeding conditions, environmental pollution, etc. may all cause abnormal living habits of animals. In addition, the change of animal physiological state and human observation illusion may be regarded as abnormal. Before determining whether this anomaly is related to the earthquake, we should identify the true and false animal anomalies.

5. What is earthquake prediction? What are the three elements of earthquake prediction?

Earthquake prediction is the prediction of the time, place, magnitude, influence intensity and damage loss of destructive earthquakes. The three elements of earthquake prediction only refer to the time, place and magnitude of the earthquake.

6. What are the long-term, short-term and imminent earthquake predictions? What is the annual earthquake trend forecast?

It is called long-term earthquake prediction to predict earthquakes that may occur in a certain place for several years to decades or even hundreds of years. Predicting earthquakes that may occur in a place in a few months to several years is called medium-term earthquake prediction. Medium-term prediction and long-term prediction of earthquakes are collectively called medium-and long-term prediction. It is called short-term prediction to predict the possible earthquakes in a certain place for several days to dozens of days or even months. Predicting earthquakes that may occur in a certain place in a few days is called imminent earthquake prediction. The annual earthquake trend forecast is a one-year scale or a little longer trend forecast made by experts organized by Seismological Bureau of China every year to the places where major earthquakes may occur in China next year.

7. What are the four countries in the world that study earthquake prediction more?

China, Japan, the United States, the former Soviet Union.

8. What is the level of earthquake prediction in China?

With the current scientific level, it is impossible to predict most destructive earthquakes. However, on the premise of fully and reasonably applying the existing practical experience and research results, it is possible to predict a certain type of earthquake to some extent under some favorable conditions.

Like other countries in the world, China's current earthquake prediction is still in a low-level exploration stage. Compared with Japan, the United States and other countries, there is still a certain gap in advanced observation technology and basic theoretical research of earthquake prediction. China has advantages in earthquake case data accumulation and field prediction experience. Frequent moderate-strong earthquakes in China provide more practical opportunities for seismologists in China to carry out experiments and predictions. In the mid-1970s, China successfully predicted destructive earthquakes, such as the Haicheng earthquake of magnitude 7.3 in Liaoning Province. Since the 1990s, there have been four earthquakes with M ≥ 5 in China, namely Menglian earthquake with M ≥ 7.3 in Yunnan, Jiashi strong earthquake swarm with M ≥ 6.3 and M ≥ 6.4 in Xinjiang, Lijiang earthquake with M ≥ 6.2 in ninglang county, Yunnan,1938+065438+1October earthquake with M ≥ 6.3 and 6.4, and1. This is unique in the world.

Generally speaking, the level of earthquake prediction in China is among the advanced in the world.

Third, earthquake disaster knowledge

1. What are the characteristics of earthquake disasters?

Earthquake disaster is the first of all disasters, with sudden, unpredictable and high frequency, and produces serious secondary disasters, which will also have a great impact on society.

2. What are the factors that affect the magnitude of earthquake disasters?

Including natural factors and social factors. Among them, there are magnitude, epicentral distance, focal depth, earthquake occurrence time, earthquake occurrence location, earthquake type, geological conditions, seismic performance of buildings, regional population density, economic development degree, social civilization degree and so on. Earthquake disasters can be prevented, and comprehensive defense work can minimize natural disasters.

3. What are the direct disasters of the earthquake?

The earthquake caused the destruction of buildings, landslides, mudslides, ground fissures, subsidence, sand blasting, water inrush and other surface damage and tsunami.

4. What is an earthquake secondary disaster?

A series of other disasters caused by the earthquake, including fire, flood, gas and toxic gas leakage, the spread of bacteria and radiation, plague and other disasters caused to life and property.

5. What are the sources of secondary disasters?

Secondary disaster sources refer to storage facilities for flammable, explosive and toxic substances, and dams that may cause floods, fires, explosions and other disasters due to earthquakes.

6. What is the most common disaster caused by earthquake?

Destruction and collapse of various buildings (structures). The resulting casualties and direct economic and property losses.

7. What is the most serious secondary disaster caused by earthquake?

It's on fire.

8. When and where did the biggest earthquake fire in the history of China occur?

1739 The fire caused by Yinchuan M8 earthquake lasted for 5 days and 5 nights.

9. Why are the secondary disasters of urban earthquakes so prominent?

Cities are highly concentrated areas of various lifeline projects, and there are various pipe networks on the ground and underground. The sources of secondary disasters are concentrated, and the secondary disasters of earthquakes are prominent.

10. When and where did the biggest earthquake and flood in the history of China occur?

1933 Flood caused by Diexi earthquake with M = 7.5 in Sichuan. During the earthquake, the mountain collapsed and blocked the Minjiang River, forming four dammed lakes. Forty-five days after the earthquake, the lake burst, causing downstream floods. The flood flooded more than 1000 miles, flooded more than 20,000 people and destroyed 50,000 mu of fertile land.

1 1. What are the factors that affect casualties?

(1) seismic intensity (magnitude and intensity);

(2) epicentral distance;

(3) Population density in the earthquake area;

(4) Seismic performance and density of the building;

(5) the season and time of the earthquake;

(6) Whether there is earthquake prediction;

(7) Whether there is an earthquake emergency plan;

(8) rescue speed.

12. Which earthquake caused the most casualties in the history of earthquakes in the world?

1556 65438+1On October 23rd, an earthquake of magnitude 8 occurred in hua county, Shaanxi Province, China, killing about 830,000 people.

13. Why is China a country with extremely serious earthquake disasters?

China is located in the Pacific Rim seismic belt and the Mediterranean-Himalayan seismic belt, with frequent seismic activities. Earthquakes in China are mainly intraplate earthquakes, which have the characteristics of shallow source, high frequency, high intensity and wide distribution. China has a large population and poor seismic performance of buildings, so the disaster rate is high. (Intra-plate earthquake refers to the earthquake that occurs inside the plate)

Four, earthquake self-help and mutual rescue knowledge and China's earthquake prevention and disaster reduction policy

1. What should urban residents do first to prevent secondary disasters during an earthquake?

Cut off the power supply and air supply to prevent fire.

2. Where should people evacuate if there is an earthquake?

High-rise buildings, narrow lanes, high-voltage lines, transformers, steep slopes and river banks.

3. How to protect yourself at home when an earthquake happens?

Keeping a clear head and quick response is the key to ensure safety. At home, you should avoid danger on the spot, don't rush to escape, and choose a safer place (such as under the bed or table) to escape; Living in a unit building, you can choose to open a small bathroom, kitchen, storage room and corner to escape; At the same time, it is necessary to turn off the power supply, gas and fire to prevent fire and gas leakage; When high-rise residents move down, they must not jump off the building or take the elevator. After the earthquake, use the gap between the two earthquakes to evacuate quickly.

4. When an earthquake happens, how to carry out personal protection outdoors?

Keep a clear head and be quick.

Outdoor, car drivers should choose the safe zone to brake, and train drivers should take emergency braking measures to brake slowly and gradually; Stay in an open place, away from high-rise buildings and high-voltage lines; Pay attention to the rolling stones on the hillside and stay away from the steep cliffs to prevent the threat of landslides and mudslides.

5. When an earthquake happens, how to carry out personal protection at work?

In the office, after the earthquake, you should quickly hide under your desk and evacuate from the stairs; Workers working in the factory should immediately turn off the machine, cut off the power supply, and then evacuate to a safe place quickly. For special departments (such as power plants, gas plants, steel mills, nuclear reactors, etc.). ), according to the special operating procedures.

6. How to carry out personal protection in public places when an earthquake occurs?

In public places, performances or competitions in theaters and gymnasiums should be stopped immediately, and the audience should hide under the row chairs, at the foot of the stage or in the orchestra pit, and organize the orderly evacuation of the audience after the earthquake; The stadium where the competition is going on should immediately stop the competition, stabilize the audience's mood, prevent panic and crowding, and evacuate to an open and safe place in an organized and step-by-step manner; Students in class should quickly hide under the desks. When the earthquake stops, under the unified command of the teacher, leave the classroom quickly and take precautions in the nearby open area to avoid crowding or jumping off the building.