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ISSN 2096-7780 CN 10-1665/P

青藏高原东南缘曲江断裂河流地貌指数对断裂活动的响应

Response of the stream geomorphic index to fault activity in the Qujiang fault on the southeastern margin of the Qinghai-Xizang Plateau

  • 摘要: 本文采用分辨率为12.5 m的ALOS_PALSAR DEM数据,利用Arcgis10.6水文分析工具提取了曲江断裂沿线的坡度、地形起伏度(RDLS)、面积高程积分(HI)和河流阶梯指数(SL)等河流地貌指数,综合分析多个河流地貌指数对曲江断裂构造活动的响应。为了分析曲江断裂的活动特征,将曲江断裂分为北西段、中段和南东段3段。其中北西段平均HI值0.34,平均SL值334;中段平均HI值0.44,平均SL值383;南东段平均HI值0.45,平均SL值415。这些结果说明中段和南东段的活动性强于北西段。通过对曲江断裂区域岩性、气候和构造活动综合分析,认为构造活动是影响河流地貌发育的主要因素。在此基础上,通过对典型地貌和露头进行野外调查,分析了曲江断裂历史地震活动情况和断裂几何结构,结果表明中段和南东段的地震活动性比北西段强。前人结果与本文河流地貌指数研究结论一致,表明曲江断裂中段和南东段的地震危险性还需进一步关注。

     

    Abstract: Based on 12.5 m resolution ALOS_PALSAR DEM data and hydrology analysis tool in Arcgis10.6, the stream geomorphic indices such as slope, relief degree of the land surface (RDLS), hypsometric integral (HI) and stream length gradient (SL) along the Qujiang fault (QJF) were extracted to analyze the impact of several stream geomorphic indices on the QJF’s tectonic activity. Previous studies divided the Qujiang fault into three segments: northwest (NW), middle, and southeast (SE), from which fluvial geomorphic indices were extracted. The average HI value of the NW segment is 0.34, and the average SL value is 334; the average HI value of the middle segment is 0.44, and the average SL value is 383; and the average HI value of the SE segment is 0.45, and the average SL value is 415. The results indicate that the middle and SE segments are more active than the NW segment. Through the comprehensive analysis of lithology, climate and tectonic activity in the QJF region, it is believed that tectonic activity is the primary factor influencing the development of stream geomorphology. Field investigations of typical landforms and outcrops were conducted to analyze the historical seismicity of the QJF and the geometry of the fault, and the results showed that the middle and SE segments are more seismically active than the NW segment. The results of the stream geomorphic indices in this paper are consistent with previous studies, indicating that the seismic hazard in the QJF’s middle and SE segment requires further investigation.

     

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