Why do earthquakes often occur in Sichuan?

The Sichuan earthquake is related to the "mountain" closest to the basin in the west. Although this inference drawn from experience is simple, it actually captures the essence of the problem. Because this terrain, commonly known as "mountain", is the famous Longmenshan fault-it is a giant crustal fault system that runs through the lithosphere, extending more than 500 kilometers from north to south and 70 kilometers wide. The hard shell originally made of rocks is almost indestructible. The reason why it can be so fractured and twisted must be that some powerful force has torn it. Therefore, scientists study the stress field of rocks in Longmenshan fault zone and find that this powerful stress really exists objectively, and it comes from the Qinghai-Tibet Plateau, a high-order region in southwest China.