The "disappearing" Ri Yitu level

Once an earthquake occurs, people will pay attention to where the earthquake is, and the earthquake is small.

This "earthquake is not big" generally refers to the size of the earthquake. In the past, we would hear the news of the Li's X.X earthquake in a certain place at a certain place, but now the news media reports rarely use the "Li's Earthquake" to describe the size of the earthquake. why?

In fact, Li's earthquake level is an early product of the development of earthquake science. How to say, take the example of technology products. The initial model is created from 0 to 1. There is always a variety of improvement and improvement. The upgrade of the version. The "Li's Earthquake" is the same as that of the "first generation". It has developed to the present, seismic science has established a set of three -dimensional seismic seismic measurement.

The initial computer can take advantage of a large room, but the computing power is limited

According to the method of earthquake -level measurement methods, the earthquake can be divided into two categories: traditional earthquakes and modern earthquakes. Let's talk about traditional earthquakes today.

The traditional earthquake level is the magnitude A of the "single frequency" seismic wave (P wave, S wave, or face wave) and the epicinal level measured by cycle T. Commonly used are local earthquake -grade ML, face wave shock MS, and body wave shock MB/MB.

Whether it is the Li's earthquake, the surface of the surface, or the body wave, there is one thing that we need to explain that these earthquake -grade standards are not directly connected with the physical process of the earthquake. Drive the formula for solving.

1. Local earthquake level

That is, the "Class Earthquake" is a kind of earthquake -grade algorithm proposed in 1935 when the American seismicist Charles Francis Richter was studied in the southern California. At first, it was set up to determine the size of the small earthquake in Southern California. The data was based on Wood-Anderson's short-term seismic instrument. This seismometer can better record the near-earthquake high-frequency earthquake waves. When studying these earthquake data, he found that different stations recorded the waveform amplitude of the same earthquake. The amplitude of the seismic waves was regular with the attenuation of the distance, which could be used to determine the seismic size.

American seismicist Charles Francis Richter

This type of earthquake algorithm stipulates that at a place with a epicenter of 100 kilometers, if the "standard seismic" (Wood -Anderson's short cycle seismic, the cycle is 0.8s, the amplification multiple is 2080) The earthquake level is 0; if the amplitude is x micron, the earthquake level is the number of them.

2. Facial waves

During the spread of seismic waves, due to the attenuation of high -frequency seismic waves is far greater than that of low -frequency earthquake waves, the role of short -term seismometers at a distance from a distance from a distance from the earthquake is limited, and it cannot record the global high earthquake.

Speaking of this, it may be a bit around. Simply put, the short -cycle seismometer is better at dealing with high -frequency seismic waves. Long -term seismic container is better at low -frequency seismic waves.

Short -cycle seismometers are generally used to study the initial and secondary vibrations and measure the fastest seismic waves. This is because these seismic waves move too fast, and the short -cycle seismic can be moved once in less than a second. The long -cycle seismometer used in a hammer generally requires about 20 seconds to complete the swing to measure the slow seismic wave movement followed by the first and after the second vibration of the crust.

On the recording diagram of the long -term seismic instrument of the high seismic, the biggest amplitude is the facial wave. In 1945, the method of B.Gutenberg (B.Gutenberg) promoted the method of determining the local earthquake ML to the Qiyuan Takaleta, and proposed the face waves. Earthquake.

3. Body wave shock level

However, there are also defects to use the measurement of surface waves, that is, there is a characteristic of the Zhongyuan Earthquake and the Shenyuan Earthquake: the facial waves are not developed, and the surface wave seismic level cannot be directly determined without face waves. Fortunately, the P -wave shock of the high earthquake is clear. In order to make up for the shortcomings, in 1945, Gudenbao proposed a bodies of the body wave. The body wave seismic level is divided into the body wave seismic MB determined by the short -cycle seismic meter and the body wave vibration -grade MB measured by the mid -length cycle seismic meter.

Because the surface wave seismic standard and body wave seismic standards are developed on the basis of local earthquake -grade standards, these three are currently referred to as the Li's earthquake system. Our topic is called the "disappearance" of the Ri Shi earthquake. It mainly refers to the disappearance of this word in the earthquake news, and the Li's earthquake system is actually used.

Three brothers of the earthquake!

In addition to the experience of experience based on experience, there is also a pain point that cannot be resolved. When using the traditional seismic standard, when the energy released by the earthquake is large, the earthquake level will not increase again. Therefore, when facing the large earthquake, the use of these earthquakes will underestimate the energy of the earthquake, and therefore, it will also be used. The development of modern earthquakes has been developed. Related content related to the modern earthquake level, and listen to it next time.

Data reference:

"Popular Science of the Earthquake" Qin Siqing

"The Development and Outlook of Earthquake Measurement Technology" Liu Ruifeng

Source: Zhenzhi Zhuojian

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