Current GPS Deformation Characteristics of Southern North China and its seismicity

Abstract

Using GPS data from 1998 to 2020, this study investigates the characteristics of the current crustal horizontal velocity field in Southern North China and adjacent areas. The relationship between deformation characteristics and earthquake activity, as well as the activity of major faults in the study area, are analyzed based on the spatial variations of regional crustal main strain rate field and surface dilatation strain rate field, and the distribution of earthquakes with magnitudes greater than or equal to 3. The results show that: (1) The GPS velocity field has an increasing trend from the northern North China Basin to the southern North China Basin and the Qinling-Dabie Orogen, but the overall movement rate is lower than that of the South China Block. (2) The distribution of earthquakes with magnitudes 3.0-5.9 is closely related to fault structures, while earthquakes with magnitudes greater than 6 are more closely related to regional crustal deformation characteristics, mainly occurring in the transition zone between areal expansion and areal compression. (3) The crustal deformation field can more intuitively indicate the movement characteristics of major faults in the study area. Major faults with strike-slip properties correspond to compressive deformation characteristics, while significant normal faults mainly exhibit extensional deformation characteristics. The segmentation and changes in the extension direction of faults are closely related to the transformation of crustal deformation characteristics. (4) These findings can provide a scientific basis for urban planning and site selection of important engineering projects, in addition to assessing the risk of earthquakes in the study area.