"Zhang Hengchuan in the Later Han Dynasty" said: "This is the way for historians to remember places.
Abnormal ground motion refers to the ground shaking before the earthquake. It is a well-known phenomenon that the ground vibrates violently during an earthquake. But before the earthquake, sometimes I feel the ground shaking. This kind of shaking is different from an earthquake, and it swings very slowly. Seismographs often can't record it, but many people can feel it.
According to the Records of Five Elements in the History of the Later Han Dynasty, there were 26 * * * earthquakes in the thirty years from the 4th year of Yonghe (AD 92) to the 4th year of Andi Yan Guang (AD 125).