汶川Ms8.0地震前的地面运动排列熵变化

将排列熵理论引入地震学领域，采用四川地震台网22个地震台的数据，每小时计算一个垂直分量排列熵值，研究汶川M_S8.0地震前地面运动排列熵的时空变化特征，试图提取与地震的孕育和发生有关的信息。结果显示，震前22 h内，震中附近形成一个排列熵高值区，这个高值区与位于龙门山断裂系北侧的高值区显示出此消彼长的态势；震中东侧的低值区在南北方向拉伸运移，并在震中东北侧向西北方向分叉凸出，汶川地震就发生在新的高值区和低值区陡变部位。结合其他学者的研究结果认为,这些现象很可能与汶川地震的发生有关联。基于地面运动排列熵的时空变化特征推测，这次地震不仅是巴颜喀拉块体与四川盆地对抗的结果，处于龙门山断裂系北侧的鄂尔多斯块体的运动也参与了此次地震的孕育和发生。

The Permutation Entropy Change of Ground Motion before the MS8.0 Wenchuan Earthquake

In this paper, we introduce the theory of entropy using seismology. We use seismic data of 22 seismic stations in Sichuan seismic network. The permutation entropy is calculated in vertical components per hour, respectively. We study the temporal and spatial variation characteristics of the permutation entropy of ground motion before the M_S8.0 Wenchuan earthquake and try to extract information about this earthquake. The results show that within 22 h before the Wenchuan earthquake, a high entropy area is formed near the epicenter. This high value area and the high value area on the north side of the Longmenshan fault system show a trend of wax and wane. The low value area on the east side of the epicenter stretches in the north-south direction, and bifurcates in the north-west direction of the epicenter. The Wenchuan earthquake occurs in the steep zone between the new high value zone and the low value zone. Combined with the findings of other scholars, we believe that these phenomena are likely to be related to the occurrence of the Wenchuan earthquake. Based on the temporal and spatial variation characteristics of the permutation entropy, we speculate that the earthquake is not only the result of the confrontation between the Bayan Har block and the Sichuan basin, but the movement of the Ordos block on the north side of the Longmenshan mountain fault system also participates in the seismogenic occurrence of the earthquake.