The activity analysis of the middle segment of the Haiyuan fault zone based on DEM terrain feature factor
The Haiyuan fault zone is an important active fault zone in northwestern China and an important part of the northeastern boundary of the Qinghai-Tibet Plateau.The study of the activity of the Haiyuan fault zone is of great significance for understanding the tectonic framework and Quaternary tectonic geomorphology of the northeastern margin of the Qinghai-Tibet Plateau,and also has a great reference for geological disaster prediction and geological risk assessment.Based on the digital elevation model(DEM)data,this study used ArcGIS and other software to extract and calculate the geomorphological parameters of each basin in this section,and quantitatively obtained the geomorphological characteristics of each basin in this section,and finally analyzing the relative tectonic activity of the study area.The hypsometric integral(HI)shows that the topographic gradients on both sides of the fault zone are significantly different.The slope of the fault zone and its southern basin is larger,the mountain is steeper,and the geomorphic erosion is stronger.The asymmetric factor(AF)indicates that the degree of tilting from west to east in the middle and eastern part of the Haiyuan fault zone in the study area is getting smaller and smaller,and the shape of the basin also changes from asymmetry to symmetry.The elongation ratio(Re)shows that the basin on the north side of the fault is significantly narrower than that on the south side of the fault,but it is more likely to be caused by early tectonic activity or other reasons.The stream length gradient(SL)shows that the slope of the river on the south side of the fault zone is larger,while that on the north side is smaller.Among the SL values of the faulted basin,the Wangtan-Huangshutan section(western section)is significantly higher than other sections,indicating that the activity of geomorphological evolution in this section is significantly higher.The seismic activity shows that the earthquakes in the eastern section of the fault are more intensive,but the western section is greatly affected by the complex fault-fold system in the Hasishan section.Therefore,the analysis results of the comprehensive topographic characteristic factors are obtained,it can be inferred that there are differences in fault activity in the middle and eastern sections of Haiyuan fault zone.The terrain on the south side is steep,undulating and the river is well developed,indicating that there may be more active tectonic activities in this area.The relatively flat terrain on the north side,weak river development and small slope index indicate that there may be weak tectonic activity in this area.
Haiyuan fault zoneActivity analysisTerrain feature factorDigital elevation model
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