Surface wave tomography based on Eikonal equation in North China Craton
Utilizing the seismic wave data recorded by temporary and permanent seismic stations deployed in the North China Craton,we obtained the phase velocity images of Rayleigh wave with 15～150 s period in the entire North China Craton by surface wave tomography based on the Eikonal equation,and inverted the S wave velocity structure in the study area.It shows that in the depth range of the upper mantle and lithosphere,the Yanshan area is characterized by high velocity,whereas low-velocity zones are found in the Datong Basin in the central North China Craton and to the south of it,as well as in the Taihang Mountains,which are connected to the low-velocity zone of the North China Basin,showing a large area of low velocity anomaly with the velocity lower than that of the northeastern margin of the Tibetan Plateau.The S-wave velocity shows that the lithospheric thickness of the Ordos block is large;it is close between the central North China Craton and the North China Basin,while larger in the Yanshan area than that in the North China Basin.This study suggests that the lithospheric destruction of the North China Craton is partitioned.There are cratonic destruction in the central North China Craton and the Yanshan area,but the degree of destruction is different.Local destruction is also found in the northern Ordos block,which,however,has little influence on the stability of the craton.The main dynamic source of craton destruction is more likely to be the westward subduction of the Pacific plate.It is found that the distribution of strong earthquakes in the central and eastern parts of the craton coincides with the craton destruction areas,and most of the strong earthquakes occur on the lithospheric strength boundary.The difference in lithospheric strength may be the reason why strong earthquake activity of the lithospheric strength boundary is higher than that of other areas.
North China CratonEikonal equationSurface wave tomographyRayleigh wave phase velocityStrong earthquake activity
万方数据
维普
