5. 1 earthquake is called moderate earthquake, which can be detected by human beings and can already cause damage, but the degree of damage should be judged according to many factors such as focal depth and epicentral distance.

To understand the magnitude, we must first understand the determination method of earthquake magnitude. The magnitude of an earthquake is obtained through a series of complicated calculations by instruments, so I won't elaborate on the specific formula. Magnitude is a measure to characterize earthquake intensity and a grade to divide the energy released by the source. I * * * is divided into nine grades. Generally, earthquakes with magnitude less than 1 are called ultrashort earthquakes. Earthquakes with magnitude greater than or equal to 1 less than 3 are called earthquakes or microseisms, and weak countries are not very shallow, so people generally don't notice such earthquakes; When the magnitude is greater than or equal to 3 and less than 4.5, it is called a felt earthquake, which can be detected by people, but generally does not cause damage; When the magnitude is greater than or equal to 4.5 and less than 6, it is called a moderate earthquake, which is the Tangshan earthquake this time; When the magnitude is greater than or equal to 6 and less than 7, it is called a strong earthquake, such as the 8.3 Ludian earthquake. When the magnitude is greater than or equal to 7 and less than 8, it is called a major earthquake, such as the 8.8 Jiuzhaigou earthquake and the 4. 14 Yushu earthquake. When the magnitude reaches more than 8, it is called a great earthquake, such as the 5. 12 Wenchuan earthquake and the 3. 1 Japan earthquake.

Earthquakes of the same scale may cause different damages, so the concept of seismic intensity is introduced. Generally speaking, after the earthquake, the epicenter was the most severely damaged and the intensity was the highest. This intensity is called epicentral intensity. The epicenter spread outward and its intensity decreased. An earthquake has only one magnitude, but the damage caused in different areas is different, that is to say, it can be divided into several different earthquake intensities. In China, the earthquake intensity is divided into 12 degrees. From people's insensitivity to instrument detection, to 12 degrees, all buildings were generally damaged, the terrain changed dramatically, and animals and plants were destroyed. Each degree is described in detail.

Having said that, I hope the answer will be helpful to everyone, and I hope everyone will be safe and not encounter an earthquake.