Intelligent Identification Method Of Active Thrust Fault Trace Based On High Precision DEM Data

In recent years with the development of space to earth observation method,the high-resolution DEM data can be obtained more convenient by high-resolution satellite images,airborne LIDAR scanning data and UAV image data,this provides solid and relibe data for the study of active tectonics.At present,researchers can identify fault distribution through visual interpretation of human eyes by generating visual shading map and slope map and other thematic maps.Due to the advantages and disadvantages of data visualization methods,there is a lot of work and requires interpreters to have a certain amount of working experience.According to the relevant research at home and abroad,the result in accordance with the actual form of geomorphic can be automatic extraction by use the method based on geomorphic features,that points out the direction for the develop of intelligent research of active tectonics.Based on that,this paper attempts to establish a surface structure positioning technology and extraction method suitable for thrust faults based on the geomorphology related to thrust faults activities by using high-resolution DEM data.Hutubi fault at the east end of Tugulu turust fault and Dushanzi thrust fault in the northern piedmont of Tianshan Mountains are selected as the study areas.The surface trace of the thrust faults in the two study areas is very obvious,and the fault scarps are mostly distributed on the mountain front and alluvial fan.At the same time,our predecessors have completed detailed field mapping of active fault geology and geomorphology in these two places,and published a large number of research results,which provide an important comparative ruler for this work.Firstly,the tectonic geomorphic types,faulting geomorphic morphology and geomorphic evolution characteristics related to thrust faults in the study area are comprehensively analyzed in this paper.Thrust faulting activity uplifted the strata on the hanging wall of the fault and formed continuous fault scarps.From the point of view of surface elevation,the original continuous upper and lower geomorphological surfaces have a steep elevation change at the fault scarps.In terms of geomorphic morphology,the scarp of thrust faults has a large slope which is different from that of the upper and lower geomorphic surfaces.In space,the scarp is a steep slope with width,and its slope face is basically the same.Then,based on the surface morphological characteristics of thrust fault scarp,we propose the data processing process of intelligent extraction of thrust fault scarp trace(1)Firstly,the data distribution of slope values of 5° ? 35° from digital terrain data is extracted to define the possible distribution locations of thrust fault scarps.(2)After that,the gully in the region is removed by generating a buffer zone with width.(3)Then,the elevation abrupt change values of the upper and lower geomorphological surfaces of the thrust fault were determined by using the Natural Break(Jenks)classification method.The plane distribution range of two adjacent geomorphic surfaces bounded by scarp is delineated,and the spatial distribution position of the steep slopes is limited by Generate a buffer surface of the appropriate width to calculate the intersection range of the two buffers.(4)The above extraction results were combined,and the main slope direction of the fault steep ridge was statistically analyzed by using the rose diagram,which further improved the accuracy of the extraction results.(5)Finally,through data density analysis,the location of the scarp was extracted.The one-key processing model tool is established in the Arc GIS program to improve the efficiency of data processing.Finally,based on the high-precision digital terrain data obtained by using UAV photogrammetry and airborne LIDAR scanning technology,the distribution of the scarp in the study area was extracted by using the above one-key automatic processing tool,the surface trace of the active fault zone is accurately located.The results of intelligent extraction are compared with the existing geological and geomorphic mapping results and the interpretation results of remote sensing data.We believe that the distribution of fault trace is basically the same,which indicates that this method has good applicability.In this paper,the uphill-facing fault scarp developed on the eastern of Dushanzi study area is extracted by using topographic relief parameters,we identified several fault traces which cann't be identified by visual interpretation and field geological and geomorphic mapping,field survey verified the existence of these uphill-facing fault scarp.It shows that this method can extract more fine micro-geomorphic structures.In this paper,an intelligent extraction tool was established to complete the extraction of the trace of the thrust fault scarp in the study area.The extraction results can not only locate the surface trace of the active thrust fault,but also indicate the scale of the scarp,this is one of the highlights of this paper.Based on the topographic relief parameters,the uphill-facing fault scarp which was not recognized by the conventional visual interpretation method was identified.It shows that the method used in this paper can achieve higher accuracy of micro-geomorphological interpretation,This is another highlight of this paper.