九寨沟7.0级地震孕育过程中的地震学特征  

Seismological Characteristics of Seismogenic Process of the Jiuzhaigou M S7.0 Earthquake

作　　者：许康生 李英 李晓雪 万文琦 鞠慧超 XU Kangsheng;LI Ying;LI Xiaoxue;WAN Wenqi;JU Huichao(Gansu Earthquake Agency,450 West-Donggang Road,Gansu 730000,China)

机构地区：[1]甘肃省地震局,兰州市730000

出　　处：《大地测量与地球动力学》2024年第5期497-502,共6页Journal of Geodesy and Geodynamics

基　　金：中国地震局地震预测研究所基本科研业务费专项(2022IESLZ04);甘肃省地震局地震科技发展基金(KY2203003)。

摘　　要：以2017-08-08四川九寨沟7.0级地震为研究对象,使用地震前震中附近10个台站宽频带地震仪数据计算地面运动速度的排列熵,讨论地面运动排列熵的时空变化与大地震孕育之间的关系。结果表明,2017-07下旬,震中附近排列熵出现两次异常变化,幅度最大的一次出现在2017-07末。10个台站均存在熵减过程,其中马尔康台(MEK)、舟曲台(ZHQ)和迭部台(DBT)的排列熵下降幅度较大,熵值分别为0.75、0.76和0.79,与均值相比分别下降12%、12%和10%。多个台站熵值的降低表明,地壳运动中有序振动信号的占比增大。震中东北部和西南部低值区的空间演变图像也表明,熵值异常变化与此次大地震的形成有关。结合以往研究结果认为,青藏高原地块的东移与华北地块和华南地块的阻挡导致此次地震的能量积累,受阻后的中下地壳物质上涌和侧挤引发九寨沟7.0级地震。We study the Jiuzhaigou M S7.0 earthquake in August 8,2017,using observation data from 10 broadband seismometers near the epicenter before the earthquake,to calculate the permutation entropy of ground motion velocity.We investigate the relationship between the temporal-spatial variation characteristics of permutation entropy and the formation of large earthquakes.The results show that there were two abnormal episodes of permutation entropy in late July 2017;the largest one occurred at the end of July 2017.There was an entropy reduction process at all 10 stations.Among them,the decreases of permutation entropy at Maerkang(MEK),Zhouqu(ZHQ),and Diebu(DBT)stations were relatively large,with entropy values of 0.75,0.76,and 0.79,respectively,which decrease by 12%,12%,and 10%compared to the mean,respectively.The decrease of entropy at multiple stations indicate that there was an orderly vibration source in the crustal movement.The spatial evolution images of the low-value areas in the northeast and southwest of epicenter also indicate that there is a correlation between the abnormal change of entropy and the formation of this large earthquake.Based on previous research results,we believe that the eastward movement of Qinghai-Tibet plateau block and its blockage by the north China block and the south China block resulted in the energy accumulation of this earthquake.The Jiuzhaigou M S7.0 earthquake was triggered by upwelling and rotation of the lower crustal material after it was blocked by the Sichuan basin.

关 键 词：排列熵 九寨沟M S7.0地震 孕震过程 地震异常 

分 类 号：P315[天文地球—地震学]