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921.
High-precision and high-resolution topographic data are the basis of quantitative study of active tectonics. The appearance and rapid development of photogrammetry method provide an economical and effective technical means for obtaining high precision terrain data. Compared with traditional measurement methods, the photogrammetry method can be carried out in a wide range without being limited by the ground visibility conditions, and the measurement cost is also relatively low. Especially in recent years, with the rapid development of computer vision theory and efficient automatic feature matching algorithm, a 3D reconstruction technique called "Structure from Motion"(SfM)was introduced into the photogrammetry method, greatly improving the automation of the photogrammetry method. This paper mainly introduces the basic principle and the development of photogrammetry method, and also summarizes the application of photogrammetry method in the study of active tectonics, and finally demonstrates the great application potential of photogrammetry method in the quantitative study of active tectonics by displaying a specific application example.  相似文献   
922.
On July 31th, 2016, a moderately strong earthquake of MS5.4 hit the Cangwu County in Guangxi Zhuang Autonomous Region. The focal depth of this earthquake is about 10 kilometers. This earthquake occurred in the junction area of Guangxi Zhuang Autonomous Region, Hunan Province and Guangdong Province. Nanning, Guangzhou, Shenzhen and other cities felt this earthquake. The Cangwu County disaster area is unique in terms of geographical position, tectonic geology, landform, economic development situation, population distribution and climate condition, etc. Based on the investigation to the earthquake hit area, and the analysis of its special natural environment, social economical conditions and humanities, seven general disaster characteristics of the Cangwu MS5.4 earthquake are summarized from the point of view of earthquake disaster emergency rescue and reconstruction. namely, the low population density in the disaster area, the single building structure type and the low-level economic development, the short duration of ground motion, the small number and low magnitude of aftershocks, no large landslide, debris flow and other secondary geological disasters caused by this earthquake, the area is prone to typhoon and other climate disasters which are likely to aggravate earthquake disaster, and the earthquake occurred in an area of weak seismicity in South China. This paper introduces the basic situation of the MS5.4 Cangwu earthquake and analyzes the seven disaster characteristics of this earthquake. In order to better respond to moderate-strong earthquake in weak seismicity regions of South China, this paper summarizes some experience and revelations about the earthquake in the MS5.4 Cangwu earthquake emergency response process, and puts forward some corresponding countermeasures of earthquake disaster reduction in weak seismicity regions in southern China. In the future work, we should pay more attention to pre-disaster prevention, and strengthen earthquake-monitoring capability. In order to reduce the casualties caused by collapse of houses, we should improve the seismic fortification standards of houses, carry out relevant researches on earthquake damage prevention measures of karst areas. And in order to carry out comprehensive disaster reduction, we should strengthen cooperation with the meteorological department, and carry out more comprehensive earthquake emergency drills.  相似文献   
923.
With the development of photogrammetry technology and the popularity of unmanned aerial vehicles (UAVs)technology in recent years, using UAV photogrammetry technology to rapidly acquire high precision and high resolution topographic and geomorphic data on the fault zone has gradually become an important technical means. This paper first summarizes the basic principle and workflow of a new digital photogrammetry technology, SfM (Structure from Motion), which is simple, efficient and low cost. Using this technology, we conducted aerial image acquisition and data processing for a typical fault landform on the northern of Caka Basin in Qinghai. The digital elevation model (DEM)with 6.1cm/pix resolution is generated and the density of point cloud is as high as 273 points/m2. The coverage area is 0.463km2. Further, the terrain and slope data parallel to the fault direction are extracted by topographic analysis method, and combined with the contour map and the slope diagram generated by the DEM, a fine interpretation and quantitative study of complex multilevel geomorphic surfaces is carried out. Finally, based on the results of sophisticated interpretation of geomorphology, we got the vertical displacements of the T1 terrace to the T3 terrace as (1.01±0.06)m, (1.37±0.13)m and (3.10±0.11)m, and the minimum vertical displacements of the T4 terrace and the T5 terrace as (3.77±0.14)m and (5.46±0.26)m, respectively, through the topographic profile data extracted by DEM. Such vertical displacement parameters are difficult to obtain directly by traditional remote sensing images, which shows the great application prospect of UAV photogrammetry technology in the quantitative study of active tectonics.  相似文献   
924.
The Hongyapu M7 1/4 earthquake in 1609 occurred on the Fodongmiao-Hongyazi fault, which is a Holocene active thrust in the middle segment of the northern Qilianshan overthrust fault zone, located in the north-eastern edge of the Tibet plateau. This earthquake caused death of more than 840 people, ruined the Hongyapu Village and had an affected area ca. 200km2. Previous work provided different opinions on the length of the earthquake surface rupture zone, such as 60km from the Bailanghe western riverbank to the Fenglehe eastern river bank, and only 11km from the Hongyazi village to eastern edge of the Hujiatai anticline. And the surface rupture zone appears in the western and middle segments of the Fodongmiao-Hongyazi fault zone. Our detailed geomorphic analysis and topographic survey found that the surface rupture zone with a total length of ca 95km is present on the new geomorphic surfaces which are slightly higher than the modern allvial-dilvial fans and riverbeds, which begins from the Hongshuiba river, Jiuquan in the west extending to the Toudaodongwan, southern Gansu in the east along the Fodongmiao-Hongyazi Fault. The surface rupture zone occurred later than 0 A D, proved by the study of trenchs and chronology. Compared to the previous research on the epicenters of the historical major earthquakes in and around the study region, this surface rupture zone is considereded to be the surface rupture zone of the Hongyapu earthquake of 1609 in Gansu provice. Average vertical co-seismic displacement of the 1609 Hongyapu earthquake is 1.1m with maximum 1.8m, dominated by thrusting. The NNW striking Xiaoqun segment shows thrust with a component of dextral strike slip and the NEE-trending East Hongshancun segment is also mainly thrust but with sinistral strike slipp. The lateral movement could be caused by the local change of the fault strike direction. Based on the length of surface ruptures, the maximum coseismic displacement and fault dipping, this event is estimated to be of ca. MW7.0~MW7.4, close to the M7 1/4 suggested by previous studies.  相似文献   
925.
The Fodongmiao-Hongyazi Fault (FHF)is one of the most active faults of the northern Qilian thrust fault zone. The 1609 Hongyazi M7 1/4 earthquake occurred on the east segment of the FHF, an area with a complex geometry at the Mayinghe River site. The seismogenic pattern of this earthquake revealed by complex surface ruptures remains unclear. In this paper, we focus on active tectonic deformation around the Hujiatai anticline (HA)in the Mayinghe River site. Combining with topographic survey via dGPS across deformed terraces and alluvial fans, a field survey of the geological section across the HA, the characteristics of the active fold and several sub-faults were constrained. Meanwhile, combined with the seismic reflection profiles passing through the anticline, the correspondence relationship between surface expressions of this tectonic and the deep structure was discussed. According to our research, the HA is a result of northward propagation of the range-front thrust fault F1. At the same time, a thrust fault F2 with dextral strike-slip motion and a thrust fault F4 were formed on the east side and north side of the HA, respectively. These two active faults accommodated local deformation. Trench results and 14C dating reveal that the 1609 Hongyazi M7 1/4 earthquake ruptured the T1 terrace in the Huangcaoba site. Combined with previous field investigations and literature about the 1609 Hongyazi earthquake, we suggest that this earthquake occurred on the range-front fault F1, and the depth of the hypocenter may be about 8~22km.  相似文献   
926.
江汉平原湖群藻相特征及其环境状况评价   总被引:1,自引:1,他引:0  
于2011年4月—2012年5月丰、平、枯3个水期对江汉平原水面面积为10 km2以上的22个湖泊进行了水质和藻类同步监测.结果显示:江汉平原主要湖泊中鉴定出藻类7门100属191种(亚种、变种),其中蓝藻门17属29种,绿藻门45属99种,硅藻门26属40种,隐藻门2属5种,裸藻门4属9种,甲藻门3属5种,金藻门3属4种;全年平均藻细胞丰度为0.93×106~84.18×106cells/L,细胞丰度以蓝藻门最高(50.65%),其次是绿藻门(29.56%),再次是硅藻门(12.30%)、隐藻门(6.19%)、裸藻门(0.56%)、甲藻门(0.39%)和金藻门(0.35%);丰水期生物量显著高于平水期和枯水期,Shannon-Wiener多样性指数年均值在1.44~2.10之间,丰水期的多样性指数略高于其他水期;藻类种类组成及优势种有明显的季节变化和空间差异.依据藻相特征的PCA分析将22个湖泊分为4个类群,不同类群具有显著不同的环境状况,氮磷营养负荷、水质状况和开发利用程度的不同是导致湖泊分化的内在原因;研究结果显示,江汉平原湖群总体上属于轻度污染状况,水体主要是中营养状态,丰水期与枯水期的湖泊生态环境状况具有显著差异;以藻相特征判断22个湖泊存在明显的时空异质性,部分湖泊因过度开发利用存在严重的富营养化风险;基于湖泊生态状况的显著时空异质性,对江汉平原湖群的管理应"因湖而异"制订科学合理的方法.  相似文献   
927.
三峡水库香溪河初级生产力及其影响因素分析   总被引:2,自引:1,他引:1  
2013 2014年采用黑白瓶测氧法对香溪河不同站点(上、中、下游及其支流库湾)和不同水深(0.5、1.0、2.0、5.0和10.0 m)的初级生产力进行原位测定.结果显示:(1)三峡水库蓄水后香溪河水域初级生产力具有显著的空间差异,支流和上游的总初级生产力大于中、下游,下游的初级生产力水平最低;初级生产力随着水深增加呈现逐渐减少的趋势;(2)初级生产力具有显著的季节差异,春、夏季显著高于秋、冬季;(3)光照强度、水温和天气对初级生产力有显著影响,水体叶绿素浓度与初级生产力极显著相关.结果显示,蓄水后改变的水文情势将香溪河的初级生产划分为明显不同的两个区域,水动力条件成为影响初级生产力的重要因子;依据初级生产力判断香溪河为富营养、自养代谢型水体.  相似文献   
928.
The Bolokonu-Aqikekuduke fault zone(Bo-A Fault)is the plate convergence boundary between the middle and the northern Tianshan. Bo-A Fault is an inherited right-lateral strike-slip active fault and obliquely cuts the Tianshan Mountains to the northwest. Accurately constrained fault activity and slip rate is crucial for understanding the tectonic deformation mechanism, strain rate distribution and regional seismic hazard. Based on the interpretation of satellite remote sensing images and topographic surveys, this paper divides the alluvial fans in the southeast of Jinghe River into four phases, Fan1, Fan2, Fan3 and Fan4 by geomorphological elevation, water density, depth of cut, etc. This paper interprets gullies and terrace scarps by high-resolution LiDAR topographic data. Right-laterally offset gullies, fault scarps and terrace scarps are distributed in Fan1, Fan2b and Fan3. We have identified a total of 30 right-laterally offset gullies and terrace scarps. Minimum right-lateral displacement is about 6m and the maximum right-lateral displacements are(414±10)m, (91±5)m and(39±1)m on Fan2b, Fan3a and Fan3b. The landform scarp dividing Fan2b and Fan3a is offset right-laterally by (212±11)m. Combining the work done by the predecessors in the northern foothills of the Tianshan Mountains with Guliya ice core climate curve, this paper concludes that the undercut age of alluvial fan are 56~64ka, 35~41ka, 10~14ka in the Tianshan Mountains. The slip rate of Bo-A Fault since the formation of the Fan2b, Fan3a and Fan3b of the alluvial-proluvial fan is 3.3~3.7mm/a, 2.2~2.6mm/a and 2.7~3.9mm/a. The right-lateral strike-slip rate since the late Pleistocene is obtained to be 3.1±0.3mm/a based on high-resolution LiDAR topographic data and Monte Carlo analysis.  相似文献   
929.
基于通过历史文献资料重建的1470—1911年黄河中下游地区36个站点的历史旱涝等级序列和矢量化的历史地图,利用EOF、REOF方法分析旱涝灾害空间特征。EOF方法展开的结果表明:前4个模态累计方差贡献率为71.85%,主要表现为第一、二、四特征向量场呈经向带状分布,第三特征向量场呈纬向分布;第一特征向量场的空间分布均为正值,说明黄河中下游地区的旱涝变化具有一致性,但是其余各特征向量场之间特点差异明显,说明在不同背景场和影响条件下,旱涝变化还存在较多局域性特征;REOF展开的结果可将黄河中下游地区旱涝划分为5个典型的敏感气候分区,这为进一步研究该区旱涝变化的区域性特征奠定了基础。  相似文献   
930.
黑龙江多宝山、铜山大型斑岩铜(钼)矿床的成岩成矿年龄以往确定主要为华力西中晚期至印支期(311-219Ma),本次研究测得辉钼矿ReOs等时线年龄为506±14Ma。它和用其他方法测定的同位素年龄有较大差别,从而为进一步讨论矿床的成矿作用提供了新的线索,推断此数据可能反映辉钼矿源岩下奥陶统酸性火山碎屑岩的年龄。研究还发现辉钼矿中187Os的含量特高,且估算储量很大,具有巨大的潜在经济价值。  相似文献   
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