Is it True That Little Earthquakes are Precursors to Big Earthquakes?

Before the earthquake, earthquake-related anomalies that occurred in nature are called earthquake precursors, and they include two types of micro-precursors and macro-precursors. Common earthquake precursor phenomena are: abnormal seismic activity, changes in seismic wave velocity, crustal deformation, abnormal changes in groundwater, changes in radon content or other chemical components in groundwater, changes in geostress, changes in geoelectricity, changes in geomagnetism, abnormalities in gravity, and abnormalities in animals , Ground sound, ground light, abnormal ground temperature, and so on. Of course, the above-mentioned anomalous changes are very complicated, and are often not necessarily caused by earthquakes. For example, the rise and fall of groundwater levels are associated with rainfall, drought, artificial pumping and irrigation. Another example is that animal abnormalities are often related to changes in weather, feeding conditions, changes in living conditions, and changes in the physiological state of the animals. Therefore, we must first identify the causes of these changes and then consider whether they are related to earthquakes. ^[1]

Human senses directly perceive earthquake precursors as macroscopic precursors of earthquakes, or macroscopic precursors for short. The more common ones are: well water rising and falling sharply, discoloration and odor, turning flower bubbling, temperature rise and fall, sudden change in spring water flow, sudden change in hot spring water temperature, abnormal animal habits, ground sound and ground light before the earthquake, etc. . ^[2]

Human senses can't perceive the earthquake precursors that can only be measured with special instruments. They are called micro-precursors of earthquakes, or micro-precursors for short. They mainly include the following categories:

Seismic anomalies: There is a certain relationship between large and small earthquakes. Although there are not many large earthquakes, there are many small and medium earthquakes. The characteristics of small and medium earthquakes are studied. It may help people predict the occurrence of a major earthquake in the future. ^[4]

If the traditional concept of continuous medium is used to treat the crustal rock layer as a solid, it must be concluded that any precursor will only appear when the stress is close to the yield stress. However, observations based on this concept have been obtained for a long time. "Clear, definitive, and few precursors with physical mechanisms" are caused by misunderstandings of crustal rock layers and inappropriate observation methods. Only by using the crustal rock layer as a discrete particle system can a correct understanding of earthquake precursors and their detection be obtained. ^[5]

According to the principles of particle physics, precursory information is mainly transmitted in the form of sluggish movement of rock blocks, compression or shear deformation of fault mud, and force chains. When earthquake precursors occur, the stagnation and sliding of each rock block are successive, and the front rock block is subjected to a large force, and the subsequent rock block forces are sequentially reduced. When it encounters a rock block with large resistance that is difficult to move or lock, all the rock blocks in the front gradually accumulate with stagnation and the resistance is increasing. The force on the lock rock block is compressed as the front fault mud is compressed. Increase. ^[5]

The detection of earthquake precursory information is first to observe and determine the force chain of accumulated energy and its state. The abnormal changes that can usually be observed can provide useful data. Stagnation of rock blocks, distribution of force chains, locking and combination of rock blocks, and accumulation of forces in rock blocks can be obtained through direct or indirect observations, which constitute effective precursor information. Precursory information on some major earthquakes can travel long distances and can last months or longer. As long as there are enough detection points, the measurement of the relative displacement of the fault boundary, the strain measurement in the sand bunker of the soil layer, the observation of the groundwater level, etc. may give the information about the sloshing movement and locking of the rock blocks, the distribution of the force chain, and the time sequence of the information propagation . For example, the phenomenon of groundwater level anomalies shifting from the periphery to the epicenter observed before the earthquake is a manifestation of the precursory time series. Observation of stress-strain steps in rocks can identify whether a rock block is stagnation slip or locked. If a non-monotonic rising step is observed and the change in the strain step value is small, if it is less than 10 ^-6 , it means that the rock block is still stagnant. Sliding, there will be no earthquake on the force chain before this rock block. If a monotonically rising step is observed, it indicates that this rock block has been locked. When the stress step continues to increase sufficiently high, an earthquake may occur in the nearby rock block area. When a rock block is under a large compressive force and an earthquake (rupture or dislocation) is about to occur, especially a large earthquake, in addition to observing the monotonic increase in the stress-strain of the rock block, other precursors of secondary effects will also be generated. Such as electromagnetic, ionization and infrasound. In order to judge the possibility of an earthquake. ^[5]

The entire movement process from the earthquake to the occurrence of the earthquake includes: the initial effect of tectonic force on the rock block, the slump movement of the rock block, the distribution and transmission of the rock force chain, the lock and combination of the rock block, and the fracture or displacement of the rock block ( Ie an earthquake). ^[5]

Many singular changes in nature are not all precursors to earthquakes, so when abnormalities are discovered, attention should be paid to distinguish them from non-seismic interference factors.

In general, the factors that cause non-seismic animal anomalies are weather changes (such as fish floating, frog migration), physiological changes (such as animal illness and estrus), environmental changes (such as water pollution), enemy infestation, and so on. Non-seismic

Seismic anomalies directly perceived by human senses are called macroscopic anomalies of earthquakes. The manifestations of earthquake macro anomalies are diverse and complex. There are hundreds of types of anomalies and thousands of anomalies. They can be broadly divided into groundwater anomalies, biological anomalies, geoacoustic anomalies, ground anomalies, earthquake clouds, and weather. Exception, etc.

Cattle, horses, donkeys, mules: panic, anxiety, do not enter ù [jiù], do not eat, squabble, fight in groups, break the reins to escape, kick the ground, plan the ground, and suddenly panic while walking.

Pig: Don't enter the pen, don't eat, bark, go out, cross the pen.

Sheep: Do nt enter the hoops, do nt eat, bark, run away, hustle.

Dogs: barking endlessly, crying, sniffing the ground, biting people, running around, moving around with their puppies, police dogs not obeying instructions.

Cat: Panic, moving the tree with the pups.

Rabbit: Do not eat grass, bark in the nest, escape from the nest in surprise.

Ducks and geese: do not enter the water during the day, do not enter the rack at night, do not eat, follow the owner, scream, and fly high.

Chicken: Don't enter the rack, bump into the rack, make trouble inside the rack, get on the tree.

Pigeon: Don't enter the nest, live outside the house, and suddenly start to fly.

Rats: Drows out in groups during the day, feels drunk like drunks, is not afraid of people, frightens, and moves around with mice.

Snake: The hibernating snake came out of the hole to freeze, freeze to death, increase in number, and gather in the snow.

Fish: floating in swarms, roaming, jumping out of the water, jumping fish in tanks, bleeding from head to tail, jumping out of tanks, making noises, sluggishness, death.

Toads (Toads): Groups of holes.

Meteorological anomaly before earthquake

Ground light

People often describe earthquake forecasting science and technology personnel as "upwardly controlling the sky, downwardly controlling the ground, and middlely controlling the air." This really makes sense. Before the earthquake, the weather was often abnormal. There are mainly sweltering heat before the earthquake, irritated people, prolonged drought or rain, yellow mist scattered, dark daylight, strange winds, and hail (blizzard) in June. ^[1]

Seismic clouds: Seismic clouds are non-meteorological cloud classifications that predict earthquakes. The color of the cloud before the earthquake is: white, gray, orange, or orange-red. The characteristics of earthquake clouds: strong winds are not easy to change their shape, the sky and clouds have obvious dividing lines, and they often appear wavy. At present, there is no unified theory for the formation of seismic clouds, only some hypotheses. ^[8]

Some scholars believe that when an earthquake occurs, huge energy is accumulated inside the earth. Therefore, from a few days before the earthquake, the geothermal heat rises, and its wave becomes an updraft, which diffuses into the stratosphere in a concentric circle shape, so that a thousand-meter-high rain cloud forms a slender straw-like earthquake cloud. ^[8]

In addition to earthquake clouds that may occur over the epicentral area, they may also occur above the stress-concentrated fault zone far from the epicentral area. At this time, when an earthquake is about to occur in the distance, the stress is already concentrated and fractured. The effect of the dilatational movement before the earthquake in the epicentral area makes the stress in the fault zone more concentrated. Thus, on this fault zone, due to tectonic movement, the rocks are squeezed, generating friction and generating heat, and a continuous hot air flow rises, thereby forming a strip-shaped seismic cloud above the fault direction. ^[8]

Because the fracture perpendicular to the direction of the stress from the source area is often the most stressed, the epicenter location is often perpendicular to the direction of the seismic cloud. In some epicentral areas at the intersection of faults, stress is highly concentrated and decays with distance, so radial seismic clouds with focal points above the epicentral area will be generated. ^[8]

Seismic clouds are also clouds. The fundamental difference between them and other clouds is that seismic clouds are meteorological responses to seismic tectonic activity. In the process of seismic monitoring and prediction using seismic clouds, how to identify seismic clouds from clouds in various poses is the first and most important task. According to the studies of some scholars, seismic clouds have the following different characteristics from other meteorological clouds: in time, seismic clouds appear suddenly; in spatial distribution, seismic clouds and fault structural belts are closely related, they are mostly formed above fault belts, The tail always points near the epicenter; in shape, it is mainly linear, as well as parallel lines, snakes, and fish scales. Some scholars believe that the underground gas in the seismic cloud system rises along the fault, mainly in the shape of long straw ropes or strips. Some scholars have classified earthquake clouds into bean-shaped clouds, honeycomb clouds, ring clouds, tail clouds, black hole clouds, bead clouds, vortex clouds, and so on.

Ray cloud: The floating cloud will take the form of extremely long rays in the sky. The position where the ray center points is the position of the central earthquake. Such a ray cloud is easy to be observed.

Seismic clouds: Seismic clouds are non-meteorological cloud classifications that predict earthquakes. The color of the clouds before the earthquake is: white, gray, orange, or orange-red. The characteristics of earthquake clouds: It is not easy to change the shape of strong winds. The sky and clouds have obvious dividing lines, and they often appear wavy. At present, there is no unified theory for the formation of seismic clouds, only some hypotheses.

There are three ways to describe the formation of seismic clouds:

Thermal theory: When the earthquake is about to occur, a large amount of heat is generated due to the accumulation of geothermal heat in the seismic zone, or due to the intense friction of the rocks in the seismic zone due to the strong gravitational force. This heat overflows from the ground surface, causing the air to warm up and generate an updraft. An "seismic cloud" was formed at high altitude, and the tail of the cloud pointed to the place where the earthquake occurred.

Electromagnetic theory: Before the earthquake, the rock had a "piezomagnetic effect" under the action of the ground stress, which caused local changes in the geomagnetic field; the ground stress caused the rock to be compressed or stretched, causing changes in the resistivity and corresponding changes in the electromagnetic field. As the electromagnetic wave affects the ionosphere at high altitude, a sharp decrease in the ionospheric plasma concentration occurs, which causes a non-free and orderly arrangement of water vapor and dust to form a seismic cloud.

The cause of radon is that radon gas, which is normally present in the formation, is composed of a variety of charged radioactive isotopes. Under the squeeze of plate movement, the amount of normal release into the atmosphere will be when the plate stress accumulates and the geostress changes suddenly. A jumping change occurs, and this change will produce a macroscopic cloud chamber effect with free water molecules in the atmosphere, which is the seismic cloud we see. The seismic cloud is actually the release trajectory of the geoduck. Geomagnetism is an index element for routine earthquake detection. The radon gas composed of a variety of charged radioactive isotopes has a cloud chamber effect and a sudden change in radon gas before the earthquake has been proved by actual measurements. Seismic clouds are concentratedly released by excessive radon gas caused by plate motion, and are released in the atmosphere and free. Water molecules form macroscopic clouds (cloud chamber effect), so the radon genesis of seismic clouds has a theoretical and practical basis.

Earthquake Precursor Anomaly

Geoacoustic anomalies are sounds from the ground before the earthquake. It sounds like a thunderous sound from a cannon, as well as heavy truck driving and strong winds. When an earthquake occurs, longitudinal waves radiate from the earthquake source and propagate along the ground, making the air vibrate and sound. Due to the large but weak potential of the longitudinal wave velocity, people only listen to the sound and move unconsciously. It needs a transverse wave to feel it . Therefore, in the epicenter area, there is often a record of "the sound in the ground before the earthquake, like the swell of the atmosphere, such as the boiling water in the tripod". If it is in the epicenter, a magnitude 3 earthquake can often hear ground sounds. Geoacoustics are the result of changes in the structure and structure of underground rocks and the movement of liquids and gases contained in them, and a large part of them are signs of imminent earthquakes ^[6] . Mastering the knowledge of geoacoustics is likely to have a better prediction and prevention effect on earthquakes. ^[9-10]

Earthquake anomalies before earthquake

Ground light anomaly refers to the light from the ground before the earthquake. Its color is diverse, and it is seen that rare mixed colors in daily life, such as silver blue, white purple, etc., but mainly red and white; their forms are also different, There are band-shaped, spherical, columnar, diffuse and so on. In general, light appears in a large range, and it usually occurs within a few hours to a few minutes before the earthquake and lasts for a few seconds. During the earthquakes in Haicheng, Longling, Tangshan, Songpan, China, and before and after the earthquake, colorful luminous phenomena appeared. Ground light often accompanies natural phenomena such as earthquakes, landslides, landslides, subsidence or sandblasting, water jets, and jets. It often moves regularly along a fault zone or an area and synchronizes with other macroscopic and microscopic anomalies. The cause is always related to Crustal movement is closely related. It is controlled by geological conditions and the surface and atmospheric conditions, and can cause different degrees of harm to people, animals and plants. The anomaly reports are all the ground light that we currently have a few seconds to 1 minute before the earthquake. Such as the Haicheng earthquake, the Lancang and Gengma earthquakes have collected similar reports. ^{[6] [10]}

Earthquake anomalies before earthquake

Ground gas anomaly refers to the mist from the ground before the earthquake, also known as the ground gas mist or ground mist. This mist has a variety of colors, such as white, black, and yellow, and is sometimes colorless. It often appears within a few days to a few minutes before the earthquake, often accompanied by strange smells, sometimes accompanied by sounds or with high temperatures. ^{[6] [11]}

Earthquake precursory anomalies

The ground motion anomaly refers to the shaking on the ground before the earthquake. He is scientifically called the foreshock. A foreshock is defined as: all vibrations that precede the maximum magnitude are called foreshocks. Some strikers can feel it. The most significant ground motion anomaly occurred before the Haicheng magnitude 7.3 earthquake on February 4, 1975. Scientists also made accurate predictions of the Haicheng earthquake through foreshocks. From the end of December 1974 to the end of January 1975, there were 17 movements in Dandong, Kuandian, Fengcheng, Shenyang, and Xiyan. ^{[6] [11]}

Earthquake Precursor Anomaly

Ground drum anomaly refers to the appearance of bulges on the ground before the earthquake. About six months before the Sichuan Luhuo magnitude 7.9 earthquake on February 6, 1973, a drum appeared on a lawn in Tuoba District, Ganzi County. It was shaped like an inverted iron pot, about 20 cm high, and cracks appeared intermittently around it. Disappeared after a few days, repeated many times, until the earthquake. Anomalies similar to floor drums also include ground fissures and subsidences. ^{[6] [11]}

Earthquake precursor electromagnetic anomaly

Electromagnetic anomalies refer to abnormalities in household appliances such as radios, televisions, fluorescent lamps, etc. before the earthquake. The most common electromagnetic anomaly is radio failure, and in the northern regions fluorescent lights are more common before the earthquake. A few days before the Tangshan magnitude 7.8 earthquake on July 28, 1976, many radios in Tangshan and its neighbourhood failed, and the sound was loud, sometimes erratic, the frequency was inaccurate, and sometimes there was continuous noise. Also before the Tangshan earthquake, some people in the city saw the fluorescent lights turned off at first and then turned on at night. Some people in Beijing turned off the fluorescent lights before going to bed, but the lights were still on.

Electromagnetic anomalies also include abnormal operation of some electrical equipment, such as abnormal microwave stations and interference with radio plants. ^{[6] [10] [11]}