How does an Earthquake Happen?

First, let's look at the internal structure of the Earth. The Earth is a multi-layered sphere with an average radius of about 6,370 kilometers. The Earth's crust, the outermost layer of the Earth, is quite thin, with an average thickness of only 33 kilometers. In conjunction with the uppermost layer of the Earth's mantle (about 2,900 kilometers thick), it forms a lithosphere about 100 kilometers thick. Due to the internal tectonic movement of the Earth, when the stratum in a certain location of the lithosphere suddenly ruptures or dislocates, the long-term accumulated energy will be rapidly released in an instant. The tremendous energy is propagated in all directions in the form of seismic waves until it reaches the surface of the Earth, resulting in ground shaking and consequently causing earthquakes.

The Kalaxiangeer mountain range, located in the epicenter of the Fuyun earthquake, protrudes westward in an arc shape, forming a large tectonic lenticular body in the Keketuohai-Ertai fault zone. This particular structure is highly prone to accumulating intense stress in this fault zone, providing material and tectonic foundation for the occurrence of the powerful Fuyun earthquake.