Why did the earth light shine before the earthquake?

1July 28, 976, midnight passed, and the pointer pointed to 3 am. Tangshan, an industrial town in northern China, is shrouded in extremely depressing air. At this time, people enjoying the cool outdoors saw colorful beams rising in the northeast, just like powerful signal lights, illuminating the earth as bright as day. Some of these beams are scattered fragments, some are like rainbow flying frames, some are like beams rising into the sky, and some are like floating balls. The color of the light beam is colorful, especially rare composite colors such as silver blue and white purple. The height is different, and the duration is long and short. This fireball once ignited in the suburbs of Tangshan, scorching the rice in the farmland. Some pupils saw this scene and thought it was dawn, so they took up their schoolbags and went to school. As a result, they made a joke. The flame dispersed and the earth began to tremble. A few seconds later, Tangshan was in ruins.

Why is this?

It turns out that this is a precursor of a strong earthquake, called terrestrial light.

Many strong earthquakes are accompanied by luminescence. This special creepy natural phenomenon was noticed thousands of years ago. China is the first country to record terrestrial light in the world. The ancient book Xiaoya at the Turn of October in the Book of Songs once described the strange acousto-optic phenomenon during the Qishan earthquake in Shaanxi Province 2800 years ago. The book says, "Ye Ye gets an electric shock and is restless. A hundred rivers boil, and the mountain family collapses. The high shore is a valley, and the deep valley is a mausoleum. " Among them, the term "Ye Ye Zhen Temple" refers to the shining ground light. Because October written in the book is a weekly calendar, which is equivalent to the current August of the lunar calendar, the thunderstorm season in Qishan and Baoji has passed, and the "October thunder and lightning" is obviously a misinformation, which should be a terrestrial light phenomenon before the earthquake. Later, in other historical materials, there are also many records about terrestrial light, such as "blue light flashes like this", "midnight morning is like day", "red at night", "red light chasing the city" and "red light in the sky is like a horse" and so on.

In foreign countries, terrestrial light has also attracted people's extensive attention. This kind of record was first seen in the chronicle of Tachilon, a Roman historian, and described the strong earthquake in Asia Minor in A.D. 17. The book says that before the earthquake, someone saw the sky shining with fire. Japan's terrestrial light record is also very early. According to Japanese seismologist Yasuhiro Yasushi, the earliest terrestrial light record in Japan can be traced back to 1500 years ago. Unfortunately, this speculation is groundless. The real recorded book is the record of three generations in 869 AD, in which the phenomenon of luminescence was mentioned when describing the earthquake and tsunami in Lu Ao, which has been more than 1 100 years ago.

It has long been known to use the phenomenon of ground light to predict earthquakes. One of the six earthquake precursors summarized by the ancients in China is the terrestrial light. "It was dark in the middle of the night, and the sky suddenly became cheerful and radiant. It is no different from Japan, it must be an earthquake. " This description has appeared in many books. However, as a strange natural phenomenon, the earth's light was scientifically explored after18th century. According to the historical records of earthquakes in Japan, before the170365438+February 5th M8.2 earthquake, a scholar, after studying the strange luminous phenomenon in the local sky, warned shogunate officials that there would be strong thunderstorms and earthquakes at night. At that time, he noticed the relationship between earthquake and luminescence, which was commendable. /kloc-In the middle of the 0/8th century, there were frequent earthquakes in Britain and Northern Europe, accompanied by earth light flashing. When the Royal Society held a meeting to discuss this issue, William Stukeley, a British scholar, first tried to explain the cause of the earth's light with surface current. Naturally, his understanding is wrong. At the beginning of the 20th century, Italian scholar Rizzo took the lead in investigating the phenomenon of earthquake luminescence in detail. He made extensive research on the luminescence phenomenon of the1September 8, 905 Calabria earthquake in Italy. Under his influence, Gary, another scholar, also collected the luminous data of the European 148 earthquake extensively, and published a research paper in the report of the Italian Seismological Society 19 10.

After 1930s, the study of earthquake luminescence entered a stage of all-round development. People no longer doubted the real existence of earth light, and theoretical hypotheses began to appear to explain this phenomenon. In these studies, Japan is particularly ahead. After 1965, Japanese scholars Yasunari, Kondo Goro, Li, etc. Used geomagnetic instruments, rotary current collectors, etc. And took the world's first photo of ground light. 1974, after studying the macro phenomenon of impending earthquake since Xingtai earthquake, Chinese scholar Zongjin Ma put forward that "terrestrial light is not only the result of earthquake derivation, but should be regarded as a unified process of impending earthquake development". In other words, ground light should be considered in connection with other phenomena that appear at the same time. With the continuous accumulation of data on terrestrial light phenomenon, people realize that its causes are not single from the complex forms of terrestrial light. Due to the short time and rare opportunity of geolight, the past geolight data often lack detailed and exact explanations, especially until today, the technical problems of instrument observation have not been solved, so the research on the causes of earthquake geolight has not yet reached a definite result and is still in the hypothetical stage.

Ground light is produced by the relative friction of rocks. Milne is a geologist who has worked in this field for many years. One day, he collected rock and mineral samples in the field. When the hammer in his hand fell on the hard rock, small sparks flew out. Milne was inspired by this phenomenon, and he was the first to put forward that terrestrial light is a luminous phenomenon caused by friction between rocks during an earthquake. 1954 Bonchkovski, a scholar of the former Soviet Union, also compared the earthquake luminescence to the sparks generated by the collision between horseshoes and stone roads.

This statement is a useful attempt to explore the causes of terrestrial light, but its explanation is only meaningful for some forms of terrestrial light, and it is difficult to work for other forms of terrestrial light. For example, some ground light occurs in mid-air and seems to have nothing to do with the rock friction on the ground; Some floor lamps are accompanied by automatic flashing similar to fluorescent lamps, which obviously cannot be explained by rubbing light. In addition, it is difficult to explain why ground light, spherical light and columnar light can be observed in a large range of seismic zones. Because according to the hypothesis of rock friction luminescence, the ground light should be mainly distributed near the fracture zone, which is consistent with the distribution direction of cracks, and the luminous part should be close to the ground. For example, during the Haicheng 1975 earthquake in Liaoning Province, a strong white light band was seen in the distribution area of magnesite in Daqingshan County, which was basically consistent with the distribution of a large number of cracks in this area. It clung to the ground for 2 ~ 3 seconds without obvious flicker, and then suddenly disappeared. This kind of terrestrial light can be explained by the viewpoint that rock friction produces light, but it is obviously not comprehensive to explain all terrestrial light in this way.

According to the capillary potential theory of water. Japanese scholar An Tian is idle and interested in electrodynamics in physics. When he sees the relative motion between liquid and solid, it is often accompanied by some electrical phenomena, that is, two layers of uneven charges will appear on the contact surface between liquid and solid. If a liquid passes through a solid capillary under pressure, there will be a potential difference between the two ends of the capillary, which is the flowing potential. This scholar germinated the capillary potential theory of water and tried to show his skill in the problem of geothermal genesis. He believes that the depth of the impact of strong earthquakes can be comparable to the scope of the ground. In the depth range affected by the earthquake, the groundwater is squeezed and moves upward through the pores of the rock, resulting in the flow potential. Terada speculated that the pressure on groundwater is equivalent to the pressure generated by a rock pillar with a thickness of 100 km. According to calculation, the potential difference it produces can reach 3 million volts. Obviously, such a huge potential difference is enough to cause high-altitude discharge and form ground light. Terada's theory has been supported by some Japanese scholars, but most international scholars have questioned this theory. In particular, American scholar MacDonald expressed doubts about the 3 million volt potential difference calculated by Terada. The American imagined various possible causes of potential difference in the earth, and studied the influence of the pressure generated by underground nuclear explosion on the flowing potential of groundwater flowing through pores in rocks and soil. It is found that the maximum potential difference that can be generated is only a few hundred millivolts in the depth range of more than 300 meters. Even if the impact of the earthquake can reach the depth of 100 km, the potential difference is only a few hundred volts, which is much smaller than what Terada said. It is impossible for such a small potential difference to cause atmospheric luminescence.

The capillary potential theory of water died out.

Theory of piezoelectric effect in time. Finkelstein and Powell are the main opponents of the capillary potential theory of water after American MacDonald. After overthrowing the theory of Japanese scholars, they put forward the theory of timely piezoelectric effect, trying to explain the formation of terrestrial light by the potential difference.

1970, finkelstein and Powell first discovered the piezoelectric effect in the process of earthquake preparation. As early as in physical experiments, scientists found that many crystals will produce opposite charges on two planes when they are squeezed or stretched. This phenomenon is called piezoelectric effect. Today, it has been widely used in various electronic equipment and instruments, as well as advanced technologies such as missiles, computers and aerospace. Piezoelectric stress is such a crystal. Because it is widely distributed in the earth's crust, earthquakes are the manifestation of sudden rupture of rock strata under long-term stress. It is conceivable that there must be piezoelectric effect in the process of earthquake preparation. Two scholars have concluded that when the chronotropic crystals are regularly arranged in the earth's crust, if the total length of the chronotropic crystals arranged along the long axis is equivalent to the wavelength of seismic waves, the seismoelectric effect will occur. If the earthquake pressure is 30-330 Pa, it is possible to generate an average electric field of 500-5000 V/cm. This electric field is enough to cause lightning-like low-altitude discharge in a storm, resulting in terrestrial light. Because the piezoelectric effect does not necessarily exist when an earthquake occurs, ground light can be seen several hours before the earthquake.

According to this theory, terrestrial light should only appear in some specific areas, where a large number of timely crystals are arranged in a directional manner. However, in the strong earthquake area where ground light actually occurs, the underground rocks are not all quartzite, but all kinds of rocks. However, regardless of the nature of underground rocks, ground light may appear, which is inconsistent with the piezoelectric effect theory. In addition, the timely piezoelectric effect theory cannot explain the unique phenomenon of "electromagnetic storm" observed in some earthquake areas.

Strange phenomena that are more difficult to explain. 1966, a few hours before the Tashkent earthquake in the former Soviet Union, an electromagnetic storm suddenly occurred over Tashkent. The dazzling white light in the sky is like a magnesium light, which makes people dizzy. What is even more surprising is that the indoor fluorescent lamp turns on itself for no reason. Scientists observed that the electron density in the ionosphere reached its peak.

Obviously, it is difficult to explain the strange characteristics of this terrestrial light with previous hypotheses.

1972, Japanese scholar An Jingfeng and others put forward the viewpoint of "lower atmospheric oscillation". They believe that because the atmosphere contains all kinds of positive and negative ions, the earth has weak conductivity. When gas molecules in the atmosphere are hit by cosmic rays from space and radioactive elements of the earth itself, these gas ions will be charged. There are often radioactive substances with radon as the main component in earthquake areas, and these radioactive substances are shaken into the atmosphere through crustal vibration, especially in the distribution area of intermediate-acid rocks and near faults containing more radioactive substances, the radon content in the atmosphere will increase significantly, which will also enhance the ionic conductivity of the atmosphere. At this time, if there is a natural electric field on the ground, it will discharge into the air on a large scale, making the ground light flicker.

After studying the Haicheng earthquake in Liaoning Province, seismologists in China found that the radon content increased obviously before the earthquake, and the electric ions in the atmosphere also increased obviously, forming a charge-intensive area over the earthquake area. After the increase of atmospheric conductivity, it may discharge and emit light under the action of ground electric field, and the rays released by large-scale discharge and radon transformation may produce fluorescence, which makes cathode fluorescent lamp emit light.

This low-level atmospheric luminescence theory is a relatively established hypothesis at present. However, some people think that the reason why fluorescent tubes emit light is related to the high-frequency seismic waves during the earthquake.

In addition, it has recently been suggested that clay minerals are also one of the light sources of the earth's light; Others once again put forward the relationship between friction heat generation of rocks and terrestrial light, and considered the formation of electric field. None of these viewpoints can satisfactorily explain the causes of ground light.

According to the existing data, terrestrial light is the general name of the luminous phenomenon caused by various reasons during the earthquake. In order to thoroughly uncover the mystery of its formation, it is necessary to strengthen the scientific observation of terrestrial light, especially to use modern advanced technology and equipment to capture various signals about terrestrial light in time, and carefully distinguish different types, and finally understand the secret of terrestrial light.

Guo, a geophysicist in China, recently learned from the experimental study of rock fracture that when a rock is fractured under pressure, it will emit a strong electron flow. Before the earthquake, rocks cracked due to crustal stress, which also produced a strong electron flow. These electron flows can enter the atmosphere through cracks in the earth's crust, ionize air molecules and produce terrestrial light, which is the latest explanation of terrestrial light in the world at present.