What are the signs before an earthquake of magnitude 8 or above?

In human history, every once in a while, a major disaster will occur, including volcanic eruptions, earthquakes, floods, landslides, tsunamis and so on. Among many natural disasters, earthquakes are serious and cause the most deaths.

Maybe you don't know the magnitude of the earthquake. Let me make a list first to help you understand.

Earthquake magnitude is divided into nine grades, generally less than 2.5 earthquake people do not feel, more than 2.5 earthquake people feel, more than 5 earthquake will cause damage. Short for magnitude.

1. Generally, earthquakes with magnitude less than 1 are called ultrashort earthquakes.

2.M≥ 1 and less than 3 is called a weak earthquake or microseism. Such an earthquake is generally not easy to detect if the source is not very shallow.

3. Earthquakes with 3.m ≥ 3 and less than 4.5 are called inductive earthquakes, which people can feel, but generally do not cause damage.

4. An earthquake with m ≥ 4.5 and less than 6 is called a moderate earthquake (e.g. Yiliang earthquake with magnitude 9.7), which can cause damage, but the degree of damage is also related to the focal depth, epicentral distance and other factors.

A magnitude less than 4.5 is called a felt earthquake, and pedestrians on the road can feel the vibration. Earthquakes larger than 4.5 and smaller than 6 are called moderate earthquakes. At this time, the house will crack, shake and crack, and people in the house can obviously feel the earthquake. Dangerous houses and old houses may collapse.

5.M≥6 and less than 7 are called strong earthquakes (such as 8.3 Ludian earthquake and 2.6 Kaohsiung earthquake).

6.M≥7 and less than 8 are called major earthquakes (such as 8.8 Jiuzhaigou earthquake, 4. 14 Yushu earthquake, 4.20 Ya 'an earthquake and 7. 18 kamchatka peninsula earthquake).

Earthquakes with magnitude greater than 6 and less than 7 are called strong earthquakes. Reinforced concrete houses will collapse and tiny cracks will form on the ground. Earthquakes with magnitude greater than 7 and less than 8 are called major earthquakes. Most reinforced concrete houses will collapse and the ground will arch, causing heavy casualties. Wenchuan earthquake belongs to this type of earthquake.

An earthquake of magnitude 7. 8 and above are called major earthquakes (such as 5. 12 Wenchuan earthquake, 3. 1 1 Japan earthquake).

Earthquakes with magnitude greater than 8 and less than or equal to 10 are called giant earthquakes. Almost all buildings will collapse on this order of magnitude, even super-reinforced military fortresses and underground vaults can't bear it.

This time, the magnitude of Lake Baikal reached 8.3, which is a huge earthquake. So what are the signs of a big earthquake like this before it happens?

We all know that the earth's surface is composed of continental plates. When the plates collide with each other, there is a great chance to induce earthquakes. When the rock stratum is squeezed or stretched, once it breaks, it will cause a huge energy explosion. These energies spread to the surface in the form of seismic waves and become earthquakes. Then there must be some signs before a big earthquake like magnitude 8 happens.

First of all, animals certainly behave abnormally. (Take Tangshan earthquake as an example)

The day before the earthquake, rats were found to "escape" in droves. The big mouse leads the little mouse and wags its tail at each other. People saw it but didn't take it seriously, just thought it might rain. In other places, hundreds of weasels ran out and migrated.

In fact, these phenomena are all "warnings" issued by nature to human beings. Unfortunately, we don't know what this "warning" wants to remind us, and we don't pay much attention to it. If people in Tangshan knew in advance that these phenomena were precursors of earthquakes, I don't think so many people would have died. Although the home can be rebuilt, life is beyond trust, and life is the most important thing.

In fact, there are many natural signs before the earthquake, such as livestock being thrown out of cages and screaming in panic, and a large number of turtles will climb ashore from fields, reservoirs and rivers to help fish in fish ponds jump or even hover in groups.

There will be some natural anomalies.

Before the earthquake, people did not feel some subtle natural changes, such as ground deformation, magnetic field and gravity changes, but these changes were often accompanied by natural anomalies. When an earthquake occurs, the well water will rise and fall for no reason, become turbid, and the water temperature will suddenly rise.

In fact, this is because the groundwater level has been affected by the earthquake. If the water suddenly bubbles, you should be extra careful. In addition, before the earthquake, people often heard low noise coming from underground. In fact, these muffled sounds are all changes in underground strata, which will appear a few minutes, days or earlier before the earthquake.

Electronic instrument abnormality

For example, some household appliances, such as radios and televisions, may flicker or break down. A few days before the Tangshan earthquake in China, many radios in the vicinity broke down and the sound was very noisy. Sometimes before an earthquake, some lights will light up for no reason, many electrical equipment will not work properly, and even electronic alarm clocks will fail.

In fact, there are many signs of earthquakes of magnitude 8 in the history of China. 1556, thirty-four years of Ming Jiajing. The epicenter was located in hua county, Shaanxi Province. According to historical data, the earthquake intensity is 8-8.3, and the intensity is 1 1 degree. The death toll reached 830,000, the highest in China's history. You know, the total population of the country was only about 63 million at that time.

There were strange signs before this earthquake, and it was also the first major earthquake with earthquake precursor records. According to Huazhou Annals, 8 hours before the earthquake, the epicenter was dizzy because of the earthquake. At the same time, there was a strange fire phenomenon underground during the earthquake, that is, light came out of the ground.

Terrestrial light is also an earthquake precursor, which will appear before the impending earthquake. Ground light, like welding light and lightning, often appears for a short time.

Speaking of which, we all know that earthquakes don't happen casually, and all kinds of precursors have hinted to us. If you have nothing to do at ordinary times, you should pay enough attention to them.