| 基于LiDAR的海原断裂松山段断错地貌分析与古地震探槽选址实例 |
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| 引用本文： | 李占飞,刘静,邵延秀,张金玉,袁兆德,王鹏,唐茂云,王朋涛.基于LiDAR的海原断裂松山段断错地貌分析与古地震探槽选址实例[J].地质通报,2016,35(1):104-116. |
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| 作者姓名： | 李占飞 刘静 邵延秀 张金玉 袁兆德 王鹏 唐茂云 王朋涛 |
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| 作者单位： | 1.中国地震局地质研究所, 北京 100029；
2.中国地震局兰州地震研究所，甘肃 兰州 730000；
3.中国地震灾害防御中心，北京 100029 |
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| 基金项目： | 中国地震局行业专项（编号：201208006）、国家自然科学基金项目（批准号：41225010）和地震动力学国家重点实验室自主课题（编号：LED2014A02） |
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| 摘 要： | 基于高精度机载Li DAR数据在GIS平台的地貌因子渲染分析,对海原断裂老虎山段松山地区古地震研究点进行高精度大比例尺(1∶1000)地貌填图,勾勒出研究点微地貌空间展布和断裂高精度几何形态。通过对松山古地震研究点2个新探槽的开挖,结合细致的探槽解译、地震事件识别与分期、年代学样品测试,得出5次37380±880BP以内的不连续古地震序列。通过对比此处已经开挖的各自相距不足150m、分布于断裂同一段落的4个古地震探槽的微地貌位置、沉积特征和地震事件信号强弱,发现即使相距不远,不同微地貌位置古地震探槽揭示的古地震现象也会有显著差别。这种差别凸显了古地震研究结果,如揭示的事件证据和个数等与探槽点位置的选取有较强的依赖性。综合对比分析表明,较低的地势、低能静水环境、高沉积速率、细粒的沉积物源区及连续的沉积环境是走滑断裂上开展古地震研究的优选地貌位置。实例表明,基于高精度地形数据对研究点开展精细地貌填图揭示微地貌时空演化,从而在探槽开挖前对古地震研究点的构造地貌优劣进行充分评价是提高古地震研究质量的必要程序,同时也显示出高精度机载Li DAR数据在活动构造研究中的重要新应用。
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| 关 键 词： | 机载LiDAR GIS分析 古地震 微地貌填图 最佳探槽点 新机遇 |
Tecto-geomorphic analysis and selection of trench sites along Haiyuan fault in Songshan site based on high-resolution airbone LiDAR data |
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| LI Zhanfei,LIU Jing,SHAO Yanxiu,ZHANG Jinyu,YUAN Zhaode,WANG Peng,TANG Maoyun and WANG Pengtao.Tecto-geomorphic analysis and selection of trench sites along Haiyuan fault in Songshan site based on high-resolution airbone LiDAR data[J].Geologcal Bulletin OF China,2016,35(1):104-116. |
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| Authors: | LI Zhanfei LIU Jing SHAO Yanxiu ZHANG Jinyu YUAN Zhaode WANG Peng TANG Maoyun and WANG Pengtao |
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| Institution: | 1. Institute of Geology, China Earthquake Administration, Beijing 100029, China;2. Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, Gansu, China;3. China Earthquake Prevention Center, Beijing 100029, China |
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| Abstract: | In this paper, the authors first carried out a large-scale(1:1000) tecto-geomorphic mapping in the vicinity of the Song-shan paleoseismic study site on the Laohushan section of the Haiyuan fault by using high resolution(1m) airborne LiDAR DEM and with the aid of topographic enhancement through GIS tools. New paleoseismic results in two trenches opened near two previously published ones less than 150m to the east were reported, which allows a comprehensive comparison of four trenches in such aspects as geomorphic setting, sedimentary environment, number of paleoseismic events and their deformation styles. The new paleoseismic results reveal a discontinuous paleoseismic sequence at 37380±880BP including 5 events with different levels of certainty. The authors found that despite the fact that these trenches are located within short distances from each other, the stratigraphic resolution and paleoseismic event evidence exposed considerable difference from trench to trench. This implies that paleosiesmic results, such as the total number and robustness of stratigraphic evidence of paleoearthquakes, strongly depend on site location. Favorable depositional environmenrts for an excellent preservation of paleoseismic record include topographic lows such as pull-apart basins allowing for low-energy and fine graine size deposition as well as high sedimentation rate for strike-slip fault. Examples presented here suggest that largescale tecto-geomorphic mapping, especially based on the high-resolution topography, is important for site selection, and such an exercise is a necesssary reconnaissance step before opening a trench to maximize the quality of paleoseismic investigation. Such a practice also shows the great potential and usefulness of airborne LiDAR data in better quantification of fault rupture behavior and fault activity in general. |
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| Keywords: | airborne LiDAR GIS tools paleoseismology tecto-geomorphic mapping new application |
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