| 基于低空遥感地貌观测的逆断层陡坎研究:以张流沟滩断层陡坎为例 |
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| 引用本文： | 马金保,张波,王洋,艾晟.基于低空遥感地貌观测的逆断层陡坎研究:以张流沟滩断层陡坎为例[J].地学前缘,2019,26(2):92-103. |
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| 作者姓名： | 马金保 张波 王洋 艾晟 |
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| 作者单位： | 北京大学 地球与空间科学学院,北京,100871;北京大学 地球与空间科学学院,北京 100871;中山大学 地球科学与工程学院,北京 100871 |
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| 基金项目： | 国家公益性重大专项“中国地震活动断层探察--南北地震带北段”(201408023) |
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| 摘 要： | 活动断层相关地貌特征的定量研究是揭示古地震和断裂属性的重要依据，其中陡坎地貌是断裂活动的重要地貌响应，是有效识别活动断裂的重要地貌标志。近年来，无人机低空遥感观测技术的不断进步，使得高分辨率地貌数据的快速获取成为现实。本研究利用无人机低空遥感地貌观测技术，对张流沟滩处的断层陡坎附近进行高分辨率数字地形数据的采集。断层陡坎位于张流沟滩河流Ⅱ级阶地上，影像采集范围为800 m×400 m的矩形区域。经过一系列的影像处理，最终获取了目标区地面分辨率为0.1 m的DEM(数字高程模型)数据。基于该DEM数据可以提取到正交于断层陡坎的高程、坡度剖面。利用高程剖面所展示的地形地貌信息，可以提取到陡坎高度为(2.81±0.05) m；利用坡度剖面所展示的坡度曲线特征，可以推断该陡坎至少经历过两次断错活动事件，并且陡坎存在向上“凸起样式”。通过探槽解译，确定该陡坎下伏断裂至少发生过两次活动事件，其中较早的地震事件接近(3.68±0.14) ka B.P.，最晚期的地震活动应为1927年古浪8级地震，两次断裂活动累计垂直位移为(2.80±0.2) m。将以上两种研究方法相比较可以发现，探槽结构分析与低空遥感获取的定量化地貌信息分析结果基本一致，均能够有效揭示古地震期次及累计的同震位移量。最终本研究将探槽揭示的地层单元的沉积、构造信息与陡坎坡度数据特征相结合，提出了基于断层传播褶皱模型的“陡坎凸起”地貌响应样式来解释陡坎存在的向上“凸起样式”。实践证明，利用无人机低空遥感地貌观测技术能够定量、半定量化揭示下伏断裂的活动信息，结合传统断裂研究手段，可以更全面解释活动断层的沉积、构造特征及地形、地貌现象。总的来说，无人机低空遥感地貌观测技术的应用可作为传统古地震研究的辅助手段，并有其独特的方法优势。
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| 关 键 词： | 活动断裂 数字地形数据 断层陡坎地貌 无人机低空遥感 |
| 收稿时间： | 2018-09-27 |
A study on the scarp of reverse fault based on geomorphological observation by low-altitude remote sensing:taking the fault scarp of Zhangliugou Beach as an example |
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| MA Jinbao,ZHANG Bo,WANG Yang,AI Sheng.A study on the scarp of reverse fault based on geomorphological observation by low-altitude remote sensing:taking the fault scarp of Zhangliugou Beach as an example[J].Earth Science Frontiers,2019,26(2):92-103. |
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| Authors: | MA Jinbao ZHANG Bo WANG Yang AI Sheng |
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| Abstract: | The quantitative study of geomorphic features associated with active faults is important for revealing paleoseismic and fracture characteristics. Faulting associated morphology, namely fault scarp, is an important geomorphological response to fault activity; therefore, it is a good geomorphic mark for effectively identifying active faults. In recent years, the rapid development of UAV low-altitude remote sensing technology has enabled rapid acquisition of high-resolution geomorphic data. In this study, we used UAV low-altitude remote sensing for geomorphologic observation to collect high-resolution digital terrain data near the fault scarp at Zhangliugou Beach. The fault scarp is located on a Class II terrace, covering a rectangular area of 800 m×400 m for imaging acquisition. After a series of imaging processing, we finally acquired DEM (digital elevation model) data with a ground resolution of 0.1 m in the target area. Based on this DEM data, elevation and slope profiles orthogonal to the fault scarp can be extracted. Using the topographic information displayed in the elevation profiles, the height of the fault scarp was determined to be 2.81±0.05 m. The slope curve feature from the slope profiles inferred that the scarp experienced at least two fault-off activity events, and the fault scarp has an upward “bulge style”. Through trench interpretation, we also determined that at least two active events occurred at the lower fault scarp: the earlier seismic event was close to 3.68±0.14 ka B.P., and the 1927 magnitude 8 earthquake was the latest activity. The cumulative vertical displacement of the two fracturing activities was 2.80±0.2 m. Comparing the above two research methods, we found that the trench structure analysis yielded basically the same quantitative geomorphological information as that obtained from the low-altitude remote sensing technology, both could effectively reveal the paleoseismic period and cumulative co-seismic displacement. Finally, by considering both sedimentary/structural information of strata units in the trench and slope profile features, we proposed the “scarp bulge” geomorphological response pattern based on the fault-propagation folds model to explain the occurrence of the upward “bulge style” of scarp. Experimental results proved that technology using UAV low-altitude remote sensing for geomorphologic observation can quantitatively or semi-quantitatively reveal the activity information of the underlying fault of scarp. When it is combined with traditional fracture research methods, this technology can more fully explain depositional and structural features as well as topography and geomorphology of active faults. And it can be used, in general, as an auxiliary method in traditional paleoseismic research for its unique methodological advantages. |
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| Keywords: | active faults digital terrain data the morphology of fault scarp UAV low-altitude remote sensing |
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