What are the signs of an earthquake?

Earthquake precursors refer to abnormal phenomena that occur before an earthquake occurs. Under the action of in-situ stress, the rock mass will gradually accumulate and strengthen the stress and strain, which will cause the earthquake source and nearby materials to occur, such as seismic activity and surface deformation. Obvious changes as well as geophysical anomalies such as geomagnetism, geoelectricity, and gravity, groundwater levels, water chemistry, and abnormal animal behavior. These abnormal changes related to the birth and occurrence of earthquakes are generally called earthquake precursors (also called earthquake anomalies). It includes two categories: seismic micro anomalies and seismic macro anomalies.

Seismic anomalies that can be directly detected by human senses are called macroscopic anomalies of earthquakes. The manifestations of macro-seismic anomalies are diverse and complex. There are hundreds of types of anomalies and thousands of abnormal phenomena. They can be roughly divided into: groundwater anomalies, biological anomalies, geoacoustic anomalies, geo-light anomalies, electromagnetic anomalies, Weather anomalies, etc.

1. Groundwater anomalies

Groundwater includes well water, spring water, etc. The main abnormalities include turbidity, bubbling, turning flowers, temperature rise, color change, taste change, sudden rise and fall, wellbore deformation, sudden depletion or gush of spring sources, etc. People summarized the proverbs about the changes in well water before earthquakes:

Well water is a treasure, and there are precursors to earthquakes.

There is no rain, the spring water is muddy, and the sky is dry and the well water is flowing out.

The water level rises and falls greatly, turning flowers and bubbling.

Some change color, and some change taste.

2. Biological anomalies

Certain organs of many animals are particularly sensitive, and they can know the occurrence of some disaster events in advance than humans. For example, jellyfish in the ocean can predict storms, and mice can Avoid mine collapses or harmful gases in advance. As for the organs of vision, hearing, touch, vibration, and balance, which ones play a major role and which ones play an auxiliary role in judgment may be different for different animals. The physical and chemical changes (vibration, electricity, magnetism, meteorology, abnormal water radon content, etc.) caused by earthquakes can often stimulate certain sensory organs of some animals and cause abnormal reactions. If the gravity of an area changes, some animals may be able to feel it through their balance organs; if there is an abnormal vibration, some animals may be able to detect it through their hearing organs. Before the earthquake, the underground rock formations had been moving slowly day by day, showing a creeping state, and there was strong friction between the fault planes. Therefore, some people believe that a frictional force will occur on the frictional fault planes only a few times to more than ten times per second. , lower than the low-frequency sound waves that human hearing can detect. Humans need more than 20 sound waves per second to feel it, but animals do not. Those animals with very sensitive senses will be terrified when they feel this kind of sound wave, resulting in abnormal phenomena such as winter snakes coming out of their holes, fish leaping out of the water, pigs and cows jumping in circles, dogs crying and wolves roaring. There are many types of animal abnormalities, including large livestock, poultry, burrowing animals, hibernating animals, fish, etc.

Animal reactions and abnormal animal behavior before the earthquake

Cattle, horses, donkeys, and mules were panicking, not entering the stables, not eating, making noises, fighting in groups, breaking their reins and running away, Abnormal phenomena of animals kicking, digging, and suddenly running away while walking (anomalies of toads)

Pigs do not enter the pen, do not eat, bark and make noise, climb over the pen, and escape outside the pen

Sheep won’t enter the pen, won’t eat, bark and make noise, run away from the pen, and make trouble in the pen

Dogs bark endlessly, cry, sniff and scratch the ground, bite people, run around and make noise, and carry puppies in their mouths Moving, the police dog did not listen to the instructions

The cat panicked and moved up the tree with the kitten in its mouth

The rabbit refused to eat grass, barked in the nest, and fled out of the nest

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Ducks and geese do not go into the water during the day, do not enter the frame at night, do not eat, follow their master closely, scream, and fly high

Chickens do not enter the frame, collide with the frame, make trouble in the frame, or climb trees

Pigeons do not enter the nest, but live outside the house, and suddenly start flying out of the nest.

Rats come out of their holes in groups during the day, in a daze like drunkenness, not afraid of people, running around in panic, and eating. Moving with mice

Snakes hibernating snakes emerge from their holes and freeze to death in the snow. Their numbers increase and they gather together

Fish float in groups, swim wildly, jump out of the water, The fish kept in the tank jump around, bleed when the head and tail are bumped, jump out of the tank, scream, become sluggish, and die

Toads (toads) come out of their holes in groups, and even run into the streets

< p> People also have a few jingles to sum up the abnormal situation of animals:

Animals have warning signs before earthquakes, so it is important to conduct mass testing and prevention.

Cattle, sheep, mules and horses are not allowed to enter the stables, and pigs are not allowed to eat. Dogs bite them indiscriminately.

Ducks don't go into the water and make noise on the shore, while chickens fly up the trees and crow loudly.

Snakes come out of their holes in the ice and snow, and rats run away with mice in their mouths.

The rabbit jumped up and down, and the fish leaped across the water and jumped in panic.

The swarms of bees are noisy, and the doves are frightened and cannot return to their nests.

Every household is observed and any abnormality is reported quickly.

In addition, some plants also had abnormal reactions before the earthquake, such as germinating, flowering, and fruiting out of season, or large areas of withering and abnormal luxuriance.

20 Earthquake Proverbs

1. As soon as the sound is reported, the earthquake comes.

2. Large earthquakes sound deep, while small earthquakes sound sharp.

3. If the sound is long, it is far away; if the sound is short, it is not far away.

4. Listen first, then move. Act quickly when you hear the noise.

5. Bump up and down, and swing back and forth for a long time.

6. If you are close, jump up and down; if you are far away, swing left and right.

7. Bumping up and down, in front of your eyes; dangling in the horizon.

8. If the house is placed east to west, the earthquake will come from the east and west; if it is placed north to south, it will come from the north and south.

9. The sand blast and water flow along the road, and the underground is the old river channel.

10. Which one has the most water and sand? Needless to say, there is waterlogged alkaline land.

11. When the tofu is squeezed, water and residue will come out; when there is an earthquake, water and sand will spray out.

12. The depression is heavy and the flat land is light; the sandy land is heavy and the land is light.

13. Brick-covered adobe walls are the least resistant to earthquakes.

14. The crispness comes from the strength, but the weakness comes from the shaking strength.

15. Parapets and eaves are the most unlucky for earthquakes.

16. The foundation should be firmer and farther away from the river; the walls should be better and the connections should be tighter; the house should be shorter and the roof should be lighter; the layout should be reasonable and the appearance should be simple. If you want to be better, learn more from each other.

17. There are earthquakes and frequent rains, either in sudden bursts or violent storms.

18. The fifteenth day of the lunar calendar falls on the first day of the Lunar New Year, so pay more attention to work at home.

19. Well water is a treasure, and the signs come early.

20. Groundwater has signs: it either rises or falls; sweetness turns to bitterness, bitterness turns to sweetness; it becomes muddy and sandy again. If you see it, please report it. Why? Noisy forecast.

3. Meteorological anomalies

People often describe earthquake forecasting technicians as "managing the sky above, the earth below, and the air in the middle." This does make sense. Before earthquakes, the weather often appears abnormal. The main symptoms include muggy heat before the earthquake, anxiety and irritability, long drought without rain or continuous rain, yellow fog, dark sunlight, strange winds, hail in June, etc. For example: floating clouds are in the shape of extremely long rays in the sky, and the location where the center of the ray points is the location of the central earthquake. Such ray clouds are easily observed by people.

4. Abnormal geoacoustic sounds

Abnormal geoacoustic sounds refer to the sounds coming from underground before earthquakes. The sound is as diverse as the sound of cannons and thunder, the movement of heavy vehicles, and the blowing of strong winds. When an earthquake occurs, longitudinal waves radiate from the source and propagate along the ground, causing the air to vibrate and make sounds. Since the velocity of the longitudinal waves is large but weak, people only hear the sound and do not feel the ground is moving. It takes the arrival of the transverse waves to feel movement. . Therefore, there are often records in the epicenter area that "before each earthquake, there is a sound in the ground, like the turbulence of the earth's air, like the swelling of boiling water in a cauldron". If you are in the epicenter, you can often hear the sound of a magnitude 3 earthquake. Ground sounds are the result of changes in the structure and structure of underground rocks and the movement of liquids and gases contained in them. A considerable part of ground sounds are signs of impending earthquakes. Mastering the knowledge of geoacoustics may have better prediction and prevention effects on earthquakes.

5. Abnormal ground light

Abnormal ground light refers to the light coming from underground before the earthquake. Its colors are various, and mixed colors rare in daily life can be seen, such as silver and blue. , white and purple, etc., but mainly red and white; their shapes are also different, including ribbon, spherical, columnar, diffuse, etc. Generally, ground lights appear over a large area, usually within a few hours to a few minutes before an earthquake, and last for a few seconds. Colorful luminous phenomena appeared during and before and after earthquakes in Haicheng, Longling, Tangshan and Songpan in my country. Earth lights often appear simultaneously with natural phenomena such as earthquakes, landslides, landslides, collapses, sand blasts, water spurts, and jets. They often migrate regularly along fault zones or an area, and are synchronized with other macro and micro anomalies. Their causes are always related to Crustal movements are closely related. And controlled by geological conditions and surface and atmospheric conditions, it can cause varying degrees of harm to humans, animals, and plants. Suspected ground light phenomenon before the Wenchuan earthquake

At present, the reports of ground light anomalies we have are all from a few seconds to a minute before the earthquake. Such as the Haicheng earthquake, Lancang, Gengma earthquake, etc. have collected similar reports.

6. Geo-gas anomalies

Geo-gas anomalies refer to the fog that comes from the ground before earthquakes, also known as ground aerosol or ground fog. This kind of fog comes in a variety of colors, including white, black, yellow, and sometimes colorless. It often appears a few days to a few minutes before an earthquake. It is often accompanied by a strange smell, sometimes accompanied by sound or high temperature.

7. Earthquake anomalies

Earthquake anomalies refer to the shaking of the ground before an earthquake. It is a well-known phenomenon that the ground vibrates violently during earthquakes. But before the earthquake occurs, sometimes the ground is shaken. This shaking is different from the earthquake. It swings very slowly and is often not recorded by seismometers, but many people can feel it. The most significant seismic anomalies occurred before the 7.3-magnitude Haicheng earthquake on February 4, 1975. From late December 1974 to the end of January 1975, they occurred in Dandong, Kuandian, Fengcheng, Shenyang, Xiuyan and other places. 17 earthquakes.

8. Abnormal floor drum

Abnormal floor drum refers to the appearance of bulges on the ground before an earthquake.

About half a year before the 7.9-magnitude Luhuo earthquake in Sichuan on February 6, 1973, a floor drum appeared on a lawn in Tuoba District, Ganzi County. It was shaped like an upside-down iron pot, about 20 centimeters high, and cracks and bulges appeared intermittently around it. It disappears after a few days and repeats many times until an earthquake occurs. Anomalies similar to floor drums include ground cracks and subsidence.

9. Electromagnetic anomalies

Electromagnetic anomalies refer to abnormalities that occur in household appliances such as radios, televisions, fluorescent lamps, etc. before earthquakes. The most common electromagnetic anomaly is the failure of radios. In northern areas, it is also common for fluorescent lamps to self-illuminate before earthquakes. A few days before the 7.8-magnitude earthquake in Tangshan on July 28, 1976, many radios in Tangshan and its neighboring areas failed. The sound was louder and quieter, sometimes non-existent, the frequency modulation was inaccurate, and sometimes there was continuous noise. Also before the Tangshan earthquake, some people in the city saw turned off fluorescent lights first turning red and then lighting up at night. Some people in Beijing turned off fluorescent lights before going to bed, but the lights were still on.

Electromagnetic anomalies also include abnormal operation of some electrical equipment, such as abnormalities in microwave stations, interference in radio plants, malfunctioning electronic alarm clocks, etc.