What is an earthquake crack angle?

It was hard to find, but I found it anyway.

earthquake intensity

The damage caused by earthquakes of the same scale is not necessarily the same; The losses caused by the same earthquake are different in different places. In order to measure the degree of earthquake damage, scientists "made" another "ruler"-earthquake intensity. On the China Earthquake Intensity Table, people's feelings and the damage degree of ordinary houses are described, which can be used as the basic basis for determining the intensity. The factors affecting the intensity are magnitude, focal depth, distance from the focal point, ground conditions and stratigraphic structure.

Generally speaking, as far as the relationship between intensity and source and magnitude is concerned, the greater the magnitude, the shallower the source and the greater the intensity. Generally speaking, after the earthquake, the damage in the epicenter area is the heaviest and the intensity is the highest; This intensity is called epicentral intensity. From the epicenter to the surrounding areas, the earthquake intensity gradually decreased. So the earthquake has only one magnitude, but the damage caused by different regions is different. In other words, an earthquake can be divided into several regions with different intensities. This is the same reason that the degree of damage from far and near is different after the bomb explodes. The amount of explosives in the bomb is like magnitude; Bombs destroy different places as much as they do.

For example, on1February 1990 10, an earthquake of magnitude 5. 1 occurred in Changshu-Taicang. Some people say that Suzhou is level 4 and Wuxi is level 3, which is wrong. No matter where it is, it can only be said that an earthquake of magnitude 5. 1 occurred in Changshu-Taicang, but this time, the earthquake intensities in shaxi town, Taicang, Suzhou and Wuxi were 6 degrees, 4 degrees and 3 degrees respectively.

In China, the intensity is divided into 12 degrees, and the impact and damage of earthquakes with different intensities are generally as follows:

People below three degrees have no feelings, only instruments can record them;

Third, people have feelings in the dead of night;

People who sleep at four to five degrees will wake up and the chandelier will shake;

Six times the ship capsized and the house was slightly damaged;

Seven to eight degrees houses are damaged and cracks appear on the ground;

Nine to ten degrees houses collapsed and the ground was seriously damaged;

Eleven to twelve degrees of devastating damage;

For example, the 1976 Tangshan earthquake, with a magnitude of 7.8 and an epicenter intensity of 11 degrees. Affected by the Tangshan earthquake, the earthquake intensity in Tianjin is eight degrees, and that in Beijing is six degrees, only four to five degrees away from Shijiazhuang and Taiyuan.