How do we judge the earthquake level?

1. Basic knowledge of earthquakes

1. What is an earthquake? What is an earthquake disaster?

Answer: Earthquakes are ground vibrations that people feel through their senses and instruments. Like wind, rain, thunder and lightning, it is an extremely common natural phenomenon. Strong ground vibrations, that is, strong earthquakes, can directly and indirectly cause damage and become disasters. All disasters caused by earthquakes are collectively referred to as earthquake disasters.

2. What are the three elements of earthquakes?

Answer: The moment of origin, epicenter and magnitude of an earthquake are called the three elements of an earthquake. The seismic moment is the moment when the earthquake occurs. The place where an earthquake occurs is called the epicenter, which is often expressed by longitude and latitude. Of course, the place name of the place must also be indicated. The size of an earthquake is represented by magnitude M.

3. What are the source, epicenter and focal depth?

Answer: The earth we live in is a slightly flat sphere, composed of three parts: the crust, the mantle, and the core. Tens of thousands of earthquakes occur every day on the earth. These earthquakes all occur in special parts of the earth's crust and mantle. We call the places where earthquakes occur inside the earth called earthquake sources.

The projection of the earthquake source on the ground is called the epicenter. In fact, the epicenter is an area, the epicenter.

The vertical distance from the source of the earthquake to the ground is called the depth of the earthquake source. According to the focal depth, they can be divided into shallow source earthquakes (h≤70 kilometers), intermediate source earthquakes (h=70~100 kilometers) and deep source earthquakes (h>300 kilometers).

4. What is earthquake magnitude?

Answer: Earthquake magnitude is a measure of earthquake energy based on certain microscopic standards. It is calculated based on the records of seismic instruments

and is only related to earthquake energy. The energy released by a magnitude 5 earthquake is equivalent to the energy released by an explosion of 20,000 tons of TNT.

The magnitude difference is 1.0 and the energy difference is 30 times. An earthquake has only one magnitude.

5. What is the Richter scale?

Answer: The Richter scale is a magnitude scale proposed by American seismologist Richter in 1935. It is based on the amplitude and period of seismic waves observed at a certain distance from the epicenter, and considering the attenuation of seismic waves from the earthquake source to the observation point, and calculating the earthquake source through a certain formula

The size of the earthquake. If seismic surface waves are used to calculate the magnitude, it is expressed as MS; if seismic body waves are used to calculate the magnitude, it is expressed as ML. In the 1960s, Richter was the most prestigious authority on seismology in the United States. Richter was very good at dealing with the news media and eager to answer questions from the public about earthquakes, so the term Richter scale soon became a way to measure the size of earthquakes. A term everyone knows. The largest earthquake measured in the world is 8.9 on the Richter scale (the 1960 Chile earthquake).

6. What is earthquake intensity? How is earthquake intensity determined?

Answer: Earthquake intensity is the intensity of the impact on the ground during an earthquake. It is mainly judged based on the macroscopic earthquake impact and damage phenomena, such as

people's feelings, reactions of objects, damage to houses and buildings, and changes in ground phenomena. Of course, the absolute intensity can also be calculated through

microscopic records of instruments. Earthquake intensity is related to factors such as earthquake size, focal depth, epicenter distance, geological conditions and other factors. Therefore, the intensity of an earthquake varies depending on the location of the damage and impact.

Our country divides the intensity into twelve degrees.

Its contents are roughly as follows:

Excerpts from the China Earthquake Intensity Scale (1980)

Intensity

Human feelings

Towards architecture Influence of objects

Other phenomena

One

No feeling

Two

Some stationary people in the room feel it

Three

A few people who were still indoors felt it

The doors and windows made a slight noise

The hanging objects moved slightly

Four

Most people indoors felt it, a few people outside felt it, and a few people woke up

Doors and windows made noises

Hanging objects swayed visibly, and utensils Noise

五

It is generally felt indoors, most people feel it outdoors, and most people wake up

Doors, windows, roofs, and roof trusses vibrate, dust falls, and plastering Hairline cracks appeared

Unstable utensils overturned

Sixth

He panicked and fled in panic.

Damage: individual bricks and tiles fell off, fine cracks in the wall

Cracks appeared on the river bank and loose soil, sandblasting water appeared in the saturated sand layer, and some brick chimneys on the ground were lightly damaged. The degree of crack turned around

Seven

Most people fled in panic.

Slightly damaged jujube is partially damaged and cracked, but does not hinder use.

The river cliff collapsed, water emerged from sandblasting, there were many cracks in the soft soil, and the brick chimney was moderately damaged.

Eight

Shaking and bumping, making walking difficult.

Medium damage: Structural damage, needing repair

Cracks in dry hard soil, most chimneys severely damaged

Nine

Sitting and standing are unsteady, and those who walk may fall.

Serious damage to the wall resulted in cracks and partial collapse, making it difficult to repair.

Cracks appear in many places, landslides and collapses are common, and brick chimneys collapse

十

Cyclists will fall, and people in unstable situations will fall. A few feet away, there is a feeling of being thrown up.

Most of the collapsed dates collapsed and could not be repaired

Landslides occurred, arch bridges were damaged, and chimneys were damaged or collapsed from the roots

November

Destruction

Earthquake ruptures last for a long time, landslides are common, and arch bridges are destroyed.

Twelve

The ground changed drastically, and the mountains and rivers changed.

7. What is the use of classifying earthquake intensity?

Answer: In addition to indicating the degree of impact and damage to the ground during an earthquake, the purpose of intensity is also a more important aspect

which is based on the intensity of active tectonic zones. Characteristics and historical seismic activity, the intensity of the earthquake area is divided, so as to calculate the maximum earthquake intensity that may occur in an area in the future, and compile a seismic intensity zoning map or earthquake risk

Danger zone map. In the construction of socialism in my country, if the distribution of earthquake intensity in a region can be understood more clearly, it will be possible to rationally plan the industrial layout of the earthquake area, as well as the structure of industrial and civil buildings. Seismic design provides favorable basis

. Avoid or reduce losses during earthquakes.

8. Who invented the world’s first seismograph?

Answer: The world’s first seismograph was invented by Zhang Heng, an outstanding natural scientist during the Eastern Han Dynasty in my country. In 132 AD, he invented the world's first instrument for observing and recording earthquakes, the wind and seismometer. It was recorded that the Longxi earthquake in Gansu Province occurred on March 1, 138 AD,

thousands of miles away from present-day Luoyang, Henan Province. The modern seismograph was only made in 1880. Its principle is basically similar to Zhang Heng's Houfeng seismometer, but it was more than 1,700 years later. Seismometers have developed rapidly and come in various types. They are highly sensitive and have achieved wireless telemetry, digital recording, etc.

9. What are the categories of earthquakes? Which type of earthquake is most harmful to humans?

Answer: Earthquakes are divided into two categories: natural earthquakes and artificial earthquakes.

Natural earthquakes are mainly tectonic earthquakes. It is caused by the cracking and dislocation of rocks deep underground, which rapidly releases the energy accumulated over a long period of time. It spreads in all directions in the form of seismic waves and causes 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

In addition, earthquakes may also occur under certain special circumstances, such as cave collapse (collapse earthquakes), large meteorites impacting the ground (meteor impact

strike 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.

Generally speaking, earthquakes mostly refer to natural earthquakes, especially tectonic earthquakes, which are the most harmful to humans.

10. What is a tectonic earthquake?

Answer: Tectonic earthquakes are caused by crustal tectonic movements. When the action of force deforms, fractures and slides rocks in the earth's crust or deeper parts, it is often accompanied by earthquakes. Such earthquakes are called tectonic earthquakes.

Tectonic earthquakes are the most common and most disastrous type of natural earthquakes. It accounts for 90% of the total number of earthquakes, and its magnitude is large. The largest tectonic earthquake ever recorded was magnitude 8.9 (Chile, May 22, 1960). In addition, the distribution of tectonic earthquakes

is consistent with the latest world active tectonic zones.

11. Which places in the world have more earthquakes?

Answer: The occurrence of earthquakes in the world is mainly concentrated in the following two areas.

The first is the Pacific Rim Seismic Belt, including the Pacific coast of North and South China and from the Aleutian Islands, Kamchatka Peninsula, through the Kuril Islands,

The Japanese Archipelago south to Taiwan Province of my country, and then Turning southeast via the Philippine Islands, it reaches New Zealand. Most of the world's earthquakes

occur in this area. The energy released by these earthquakes accounts for about 76% of the energy released by all earthquakes in the world.

The second is the Himalayan Date-Mediterranean Seismic Zone. Including the western Indonesia through Myanmar to my country's Hengduan Mountains and Himalayas

area, across the Pamir Plateau, through Central Asia to the Mediterranean and its surrounding areas, there are many and very strong earthquakes, and they are released

< The energy of p> accounts for about 22% of the energy released by all earthquakes in the world. Our country is right between two major earthquake zones, so it is a country with many earthquakes.

12. What are the main earthquake zones in my country?

Answer: Areas where earthquakes occur more frequently and are relatively strong are called seismic zones. According to the classification of the Institute of Geophysics, Chinese Academy of Sciences, my country can be roughly divided into twenty-three seismic zones (as shown in the picture). They are: 1. Tancheng Zaolu River Zone, that is, Cong'an

The Huilu River passes through Tancheng, Shandong to the northeastern area. 2. Yanshan belt. 3. Shanxi belt. 4. Weihe plain zone. 5. Yinchuan belt. 6.

Liupan Mountain Belt. 7. East Yunnan belt. 8. Tibet Chayu Belt. 10. Southeast coastal zone. 11. Hebei Plain. 12. Hexi Corridor

Belt. 13. Tianshui jujube and Lanzhou belt. 14. Wudu Zaoma side belt. 15. Kangding jujube and Ganzi belt. 16. Anning Valley Belt. 17. Teng

Chongzao Lancang belt. 18. Western Taiwan. 19. The eastern belt of Taiwan. 20. Western Yunnan belt. 21. The southern edge of Tarim. 22. South

Tianshan belt. 23. North Tianshan belt.

13. What are the regularities in the time distribution of earthquakes in my country?

Answer: The most important and common law in the time distribution of earthquakes in my country is the periodicity and repeatability of seismic activity.

The seismic activity cycle consists of two phases: quiet and active. Due to the differences in tectonic activity in various regions, the length of seismic activity periods

is different. The seismic activity cycle in the east of my country is generally longer than that in the west (except Taiwan). A cycle in the east is about 300 years. In the west, it is about 100 to 200 years. In Taiwan, it is several decades. Generally speaking, the seismic activity period at the edge of the plate is shorter, and the seismic activity period inside the plate is longer. An earthquake cycle can be further divided into shorter periods, which we call earthquake curtains. Whether there are longer periods is still difficult to determine because the historical earthquake records are too short. .

Earthquake repeatability refers to the phenomenon of earthquakes occurring repeatedly in the same place. Generally speaking, the larger the earthquake, the longer the repetition time; the smaller the magnitude, the shorter the repetition time.

However, in different earthquake zones and zones, due to differences in the intensity of tectonic activity, the repetition time of earthquakes of the same magnitude is also different.

According to statistics, the recurrence time of earthquakes with magnitude 6 can range from decades to hundreds of years, and the recurrence time of earthquakes with magnitude 7 or above is more than a thousand or even thousands of years.

14. What is earthquake migration?

Answer: Earthquake migration refers to the phenomenon that strong earthquakes occur one after another according to certain time and space rules. They are the rules of changes in stress concentration points in a unified regional stress field. The spatial and temporal scale of earthquake migration can be large or small, long or short. A migration process can be completed along a fault zone in more than ten years (such as the 1920 Haiyuan 8.5 earthquake in the Qilian Mountain seismic zone from southeast to northwest, the 1927 Gulang magnitude 8 earthquake and Changma magnitude 7.5 earthquake in 1932); it can also be used in a seismic area, using seismic zones as migration units, to complete a migration process within hundreds of years (such as The strong earthquakes in the North China earthquake zone from 1484 to 1732 mainly occurred in the Shanxi belt, while the strong earthquakes from 1815 to 1976 migrated from west to east to the North China Plain seismic belt); in addition, there were earthquakes along the p>

Latitude for longer distance migration.

The regular migration of seismic activity is only a part of the seismic activity, and a considerable part of the seismic activity does not show a regular

migration process.

15. How are distant earthquakes, near earthquakes and local earthquakes divided?

Answer: Far earthquakes, near earthquakes, and local earthquakes are classified according to the distance from the seismic station to the epicenter. Earthquakes with an epicenter distance greater than 1,000 kilometers

are called telequakes, earthquakes with an epicenter distance within 100-1,000 kilometers are called near earthquakes, and earthquakes with an epicenter distance within 100 kilometers are called local earthquakes

shock. The 7.3-magnitude earthquake that occurred in the Liaoning sea area and Yingkou area on February 4, 1975 is considered a local earthquake for the Jinxian Earthquake Observation Station in southern Liaoning, a near earthquake for the Beijing Earthquake Observation Station, and a near earthquake for the Xinjiang Earthquake Observation Station. Even if you stand still, you will be shaken far away. This means that earthquakes in the same place are affected by different seismic stations. As for earthquakes in different areas by the same seismic station, the same principle applies.

16. Why are earthquakes and tsunamis such a threat to some places?

Answer: Because places like Japan and Chile are places prone to earthquakes and tsunamis. They are close to each other, so of course they are under greater threat

especially since they are on the verge of many disasters. In deep trenches, the water is already very deep not far from the land, and tsunamis can hit the shore while still maintaining a lot of energy. It is different if there is a wide continental shelf on the shore. At this time, the waves will lose a lot of energy due to friction with the seabed on the way forward. Islands and reefs on the seaside also play the role of breakwaters. By the time it reaches the shore

it is at the end of its strength and can no longer cause any harm.

This is the case along the coast of our country, so although the tsunami caused by the Chilean earthquake in 1960 was very large and caused disasters in places like the Philippines and even Japan, it had no impact on our country

ring.

17. How does volcanic activity cause earthquakes?

Answer: Some earthquakes in the world are caused by volcanic activity. People call such earthquakes volcanic earthquakes. It accounts for about

7 of the total number of earthquakes.

Volcanic eruptions are just like blasting underground. Of course, they will cause the earth to shake, sometimes on a large scale. Because the energy possessed by some

volcano eruptions is similar to or even exceeds the energy released by a major earthquake, and the vibration it can cause

is not small. For example, the Sakurajima volcano in Japan erupted in 1914, with an energy of 4.6×1025 ergs, and the vibrations produced were equivalent to a magnitude 6.7 earthquake.

Earthquakes also occur before and after volcanic eruptions. Because before a volcanic eruption, a large amount of magma has accumulated and expanded in the crust there, which can not only cause new fractures in the rock formations, but also cause the original fractures to change again, so earthquakes generally occur.

Produced. Of course, earthquakes are a sign that a volcano is about to erupt. After a volcanic eruption, a large amount of magma quickly erupted from the surface. The magma deep underground

had no time to replenish, leaving a space where the rock formations would collapse and fracture, causing some large-scale disasters

Small earthquake.

18. How large is the area affected by a moderately strong earthquake?

Answer: Generally speaking, the affected area of ??a moderately strong earthquake is as follows: (1) 5.0-5.4 magnitude earthquake, the epicenter intensity is mostly six degrees, and its

area is less than 500 square meters kilometer. (2) For earthquakes with a magnitude of 5.5-5.9, the epicenter intensity is mostly seven, and their area does not exceed 200 square kilometers; the area of ??the six-degree area is only a few hundred square kilometers. (3) For earthquakes with a magnitude of 6.0-6.4, most of them have an epicenter intensity of eight degrees, covering an area of ??several tens of square kilometers; the seven-degree area does not exceed 200 square kilometers, and the six-degree area covers hundreds of square kilometers. It is seven degrees, which is the same as the result of a magnitude 5.5-

5.9 earthquake. (4) 6.5-6.9 earthquake, half of the epicenter intensity is eight degrees, and the result is the same as the 6.0-6.4 earthquake; the other half is nine degrees, its area is less than 100 square kilometers, and the eight-degree area does not exceed 500 square kilometers, while the seventh-degree area is within 1,500 square kilometers

.

19. How many casualties can a moderately strong earthquake cause?

Answer: Statistics show that the casualties caused by a moderately strong earthquake are roughly as follows: (1) 24 casualties caused by earthquakes with a magnitude of 5.0-5.9.

Accounting for 24. Earthquakes that only cause casualties are even fewer, accounting for only 11.5. The maximum number of deaths in an earthquake with a magnitude of over 5 is 117.

And earthquakes that killed more than 29 people all occurred at night.

(2) 43 earthquakes with a magnitude of 6.0-6.9 caused casualties, but only 35 people died. The maximum number of fatalities in an earthquake

is 600.

20. How will an earthquake of around magnitude 5 cause damage to buildings?

Answer: The epicenter intensity of an earthquake of about magnitude 5 (4.6?/FONTgt; 5.4) is mainly six degrees, and the damage to buildings is: Category I

Many damaged houses , a few were damaged and some were dumped. Many Class II and III houses were slightly damaged. Category IV house damage. The archway,

bricks, stone towers and courtyard walls were slightly damaged.

〔Note〕

(1) House type

Category I: simple shacks, made of adobe, eggs and rubble, with grass and mud roofs Rough house.

Category II: generally low-level private houses and old decaying wooden frame houses made of rammed earth or brick, egg or rubble masonry.

Category III: wooden frame buildings (such as palaces, temples, towers, etc.) and new masonry houses.

(2) General building damage

Slight damage: mortar is scattered, there are small cracks or small pieces peeling off the wall surface, and occasionally loose attachments slip off.

Damage: There are small cracks in the wall, larger cracks at the joints, and some local collapses; the wooden frame has a few tenons, and the top of the chimney is twisted

Injury.

Damage: Large cracks in the wall, some parts collapsed, the wooden frame was tenoned, the column feet moved, part of the roof was damaged, and the chimney fell down.

Toppling: All or most of the walls, floors and roof of the building collapse, or the roof moves, the walls deform and collapse, the wooden frame is significantly skewed

and the components are broken.

(3) Damage level of multi-story reinforced concrete frame (including infill walls) houses.

Basically intact: The frame columns and beams are basically intact, with small cracks in some walls or parts. It can still be used without repair.

Slight damage: Some frame columns and beams have slight cracks, and some walls have obvious cracks; small buildings on the roof are obviously damaged and can be used with a little repair

Medium damage: Some frame columns have slight cracks or individual columns have obvious cracks; individual walls have serious cracks or are partially broken, and can continue to be used after major repairs

Severe damage: some frame columns and main bars buckled, the concrete shattered and collapsed, and some floors collapsed, making it difficult to repair.

Collapse: less than 50% of the house frame remains and must be rebuilt.

21. How will an earthquake of magnitude 6 or so cause damage to buildings?

Answer: 5.5?/FONTgt; The epicenter intensity of a 5.9-magnitude earthquake is mainly seven degrees. The building damage phenomenon is: most Class I houses are damaged

and a few are toppled. Most Category II houses were damaged and a few were destroyed. Most of the Class III houses were slightly damaged and many were damaged. Not very

The strong courtyard walls were rarely damaged and some may have collapsed. Archways, masonry towers and factory chimneys may be damaged.

The epicenter intensity of earthquakes measuring 6.0-6.4 is mainly eight degrees, causing the following damage to buildings: Most Class I houses were damaged and many collapsed

Many Category II houses were damaged and a few collapsed. Most of the Category III houses were damaged, and a few were damaged (some may have fallen over). The courtyard wall

was damaged and partially collapsed. Many stone monuments have been moved or fallen down. Some underground pipe joints were damaged.

Multi-story reinforced concrete frame houses, due to differences in foundation types, house seismic design standards and construction quality,

At present, what extent will an earthquake with a seismic intensity of eight degrees cause? There is no unified standard for the damage. Therefore, according to the survey results of the 1975 Liaoning Sea Area 7.3 earthquake, Yingkou City suffered damage with an earthquake intensity of 8 degrees. Basically

50% are in good condition, 17% are slightly damaged, and 33% are moderately damaged.

22. How will an earthquake with a magnitude of around 7 cause damage to buildings?

Answer: The epicenter intensity of a 6.5-.9 magnitude earthquake is eight and nine degrees. If considered at nine degrees, the damage to the building will be: Category I houses

Houses Most dump. Many Category II houses collapsed. Many Category III houses were damaged and a few collapsed. Most of the courtyard walls collapsed, and some of the stronger ones also collapsed. Archways, towers and factory chimneys are often damaged or even toppled. Many stone tablets were overturned. There are some cracks in underground pipes.

The epicenter intensity of a magnitude 7.0 to 4 earthquake is generally nine degrees, and can reach up to ten degrees in some cases. The destruction of the ninth degree is as described above. Ten degrees caused great damage to buildings

Many Category III houses collapsed. The rails were slightly bent and underground pipes were broken.

23. Which earthquake had the widest impact in my country’s history?

Answer: The earthquake with the widest impact in the history of our country was the 8.5-magnitude earthquake that occurred in Haiyuan, Ningxia Hui Autonomous Region on December 16, 1920.

The epicenter intensity was 12 degrees , the focal depth is 17 kilometers, and the epicenter is located at 36.5° north latitude and 105.7° east longitude. This earthquake

The earthquake affected Ningxia, Qinghai, Gansu, Shaanxi, Shanxi, Inner Mongolia, Henan, Hebei, Beijing, Tianjin, Shandong, Sichuan, Hubei, Anhui, Jiangsu, 17 provinces, municipalities and autonomous regions including Shanghai and Fujian. The affected area reaches more than 3 million square kilometers.

24. Why should we popularize and publicize earthquake knowledge?

Answer: Earthquakes, earthquake prediction and disaster prevention and mitigation have strong social aspects, but the current phenomenon of earthquakes is often mysterious and vague in public opinion

. At present, it is difficult for the public to understand the difficulty and complexity of earthquake prediction when science and technology are not yet able to accurately predict earthquakes. They often mistake post-earthquake summaries for pre-earthquake predictions or internal debates. Opinions spread to the society

causing social chaos; the vast majority of the public or some leading departments still do not know what they should do before and during the earthquake

to make decisions on earthquake disaster prevention and reduction contribute. At present, most of the books and periodicals on earthquakes are highly specialized and use expert language and concepts that are difficult for the public to understand. Therefore, in order to enable all social strata and every member of society to consciously take correct social actions regarding earthquakes, earthquake prediction, and earthquake avoidance and disaster reduction

, we must vigorously popularize and publicize earthquake knowledge work, so that people who have mastered earthquake knowledge can promptly identify macroscopic anomalies and report them in a timely manner; enhance earthquake monitoring capabilities and awareness of earthquake resistance; at the same time, due to the knowledge of earthquakes, , can enable the general public to enhance their ability to identify and resist earthquake rumors and misinformation, and greatly reduce earthquake-related losses

; on the other hand, the popularization and publicity of earthquake knowledge can enable leaders at all levels to both Understand the seriousness of earthquake disasters and master

certain knowledge of earthquake countermeasures, so that you can be mentally, organizationally and materially prepared before an earthquake, and be able to respond quickly after an earthquake

Implement disaster relief measures to reduce losses. The popularization and publicity of earthquake knowledge can also attract people with lofty ideals in society who are committed to the development of human welfare undertakings to join the ranks of earthquakes and promote the development of earthquake science and technology. Therefore, the popularization and publicity of earthquake knowledge is a strategic and regular task. If this task is done well, it is possible to minimize earthquake disasters.

25. Which was the earliest recorded earthquake in China?

Answer: An earthquake occurred in Puzhou (now known as) during the Yao and Shun era of China (23rd century BC).

26. Which was the largest earthquake in the history of Guangdong Province?

Answer: There was a magnitude 7.3 earthquake in South Australia on February 13, 1918.

27. Where did the largest reservoir-induced earthquake in my country occur since recorded history?

Answer: On March 19, 1962, my country's largest reservoir-induced earthquake occurred in the Xinfengjiang Reservoir Dam area in Heyuan, Guangdong. The magnitude

was 6.1.

28. What earthquakes have had a greater impact on Guangdong Province since the founding of New China?

Answer: The earthquakes that have had a greater impact on Guangdong Province since the founding of New China include: the 1962 Xinfengjiang earthquake in Heyuan, Guangdong, with a magnitude of 6.1, the 1969

Yangjiang, Guangdong earthquake with a magnitude of 6.4, the 1994 There were earthquakes with a magnitude of 7.3 in the Taiwan Strait in 2004, and earthquakes with a magnitude of 6.1 and 6.2 in the Beibu Gulf in 1994 and 1995.

29. Where are the earliest seismic stations and telemetry stations built by my country?

Answer: In 1930, my country's first self-built seismic station, the Jiufeng Seismic Station in Xishan, Beijing, was built under the leadership of Mr. Li Shanbang and Mr. Qin Xinling

In 1937, the Japanese invaders launched Observations were stopped after the war of aggression against China. In 1966, the Beijing telemetry network was completed, with 8 sub-stations.

30. Are there any signs of earthquakes?

Answer: Before an earthquake, earthquake-related anomalies that occur in nature are called earthquake precursors, which include microscopic precursors and macroscopic precursors.

Common earthquake precursor phenomena include: (1) Abnormal seismic activity; (2) Changes in seismic wave velocity;

(3) Crustal deformation; (4) Abnormal changes in groundwater; (5) Radon gas content in groundwater or Changes in other chemical components;

(6) Geostress changes; (7) Geoelectric changes; (8) Geomagnetic changes; (9) Gravity abnormalities; (10) Animal abnormalities;

(11) Ground sound; (12) Ground light; (13) Ground temperature abnormality, etc.

Of course, the above-mentioned abnormal changes are very complex and are often not necessarily caused by earthquakes. For example, the rise and fall of groundwater levels is often related to rainfall, drought, artificial pumping and irrigation. Another example is that animal abnormalities are often related to changes in weather, changes in feeding conditions, changes in living conditions, changes in the physiological state of the animals themselves, etc. Therefore, we must first identify the causes of these changes and then consider whether they are related to earthquakes.

31. What were the abnormal changes in groundwater before the earthquake? What distractions should I watch out for?

Answer: The rise and fall of groundwater levels, changes in color, taste, blooming, bubbling, and sudden changes in hot spring water temperature may all be signs of an earthquake

However, changes in groundwater are a very complex phenomenon, and care must be taken to eliminate interference from rainfall, drought, river fluctuations, typhoons, artificial pumping and irrigation, environmental pollution and other factors.

32. What abnormal reactions did fish have before the earthquake?

Answer: Fish such as catfish, crucian carp, herring, grass carp, silver carp, loach, goldfish, shark and some deep sea fish all react.

It manifests as tumbling, jumping, swirling, swimming wildly, and floating in groups on the water surface. Some of them scream, some are in a coma, the fish

belly turn upward, or even die.

33. Which ground animals have abnormal reactions before earthquakes? How does the abnormality manifest?

Answer: Before the earthquake, rabbits, cats, chickens, dogs, sheep, pigs, cattle, horses, donkeys and other large livestock all had abnormal reactions, which were generally manic

and melancholic. Two types. The former is characterized by barking, sniffing, scratching, biting, running around, and making noises. Police dogs do not listen to instructions. Pigs, sheep and large livestock do not enter the pen, do not eat, and make trouble in the pen. The cat broke away from the reins and ran away; the latter appeared to be sluggish and not eating, while the cat was frightened

Fleeing, scratching and making chaos, some moved with kittens in their mouths, some ran away before the earthquake and came back after the earthquake.

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

Answer: Earthquake forecasting is the prediction of the time, location, magnitude and impact of destructive earthquakes. The three elements of earthquake prediction

refers to the time, location and magnitude of the predicted earthquake.

35. What are long-term, medium-term, short-term and imminent earthquake predictions? What is earthquake annual trend prediction?

Answer: (1) Long-term earthquake forecast refers to the forecast of areas where destructive earthquakes may occur in the next 10 years; (2) Earthquake

Medium-term forecast refers to the forecast of the future Forecast of areas and intensity of destructive earthquakes that may occur within one or two years; (3) Short-term earthquake forecast refers to the forecast of the time, location, and magnitude of an earthquake that will occur within three months; (4 ) Imminent earthquake forecast refers to the forecast of the time, location and magnitude of an earthquake that will occur within 10 days; (5) Annual earthquake trend forecast is carried out by the China Earthquake Administration every year Organize experts to make trend predictions on locations where devastating earthquakes may occur in the country in the next year.

36. What is the main reason why earthquake prediction is difficult?

Answer: The main reasons for the difficulty of earthquake prediction are: first, the complexity of the earthquake phenomenon itself; second, earthquakes mostly occur deep underground

The current level of science and technology It is difficult to directly detect the situation deep in the earthquake source; third, strong earthquakes (especially earthquakes with magnitude 7 or above) occur less frequently, so there are few opportunities for practical forecasting.

37. What is the current level of earthquake prediction in my country?

Answer: The current level and status of earthquake prediction in my country can be summarized as follows: we have some understanding of the principles and laws of earthquakes, but we are far from fully understanding them; under certain conditions It is possible to predict certain types of earthquakes to a certain extent, but it cannot predict all earthquakes; medium-term forecasts measured in years have a certain degree of credibility, but those measured in days The success of short-term forecasting is limited to a very small number of special types of earthquakes.

38. Which was the first successful earthquake prediction in the world that achieved obvious disaster reduction results?

Answer: Our country's seismologists successfully predicted the 7.3-magnitude earthquake that occurred in Haicheng, Liaoning on February 4, 1975, which was called "the first in the history of earthquake science" by the world's scientific and technological community

miracle".

39. Why is 1966 called a milestone in earthquake prediction in China?

Answer: On March 8 and March 22, 1966, strong earthquakes with magnitudes 6.8 and 7.2 occurred in the Xingtai area of ??Hebei Province, respectively, causing heavy losses.

Premier Zhou Enlai visited the earthquake scene several times to guide the earthquake relief work, listened extensively to the opinions of seismologists and experts from all fields, and issued a great call to earthquake workers to engage in earthquake prediction. Therefore, 1966 is called a milestone in earthquake prediction in China.

40. How to judge earthquake rumors and misinformation?

Answer: (1) "Earthquake information" with feudal superstition or bizarre legends, such as that a certain place is about to sink into the sea, etc., which have no scientific basis, are purely earthquakes. rumor.

(2) It is said that a foreign institution or an expert authoritative person put forward a "forecast opinion". This kind of information is not in compliance with the national earthquake forecast regulations through informal channels.

believe.

(3) It is said that the magnitude of the earthquake is very large (magnitude 8, 12, etc.) or the time, location and magnitude of the earthquake are very specific (such as a certain day, a certain time

, a certain area , a certain village or what time and level, etc.), this kind of information that is inconsistent with scientific reality and the current forecast level should be regarded as rumors or misinformation.