近断层速度脉冲与震源机制的关系浅析   总被引：1，自引：1，他引：0  

罗全波  陈学良  高孟潭  李宗超  李铁飞  张振 《震灾防御技术》2018,13(3):646-661

本文初步分析了近断层速度脉冲的成因和特点，主要包括方向性效应与滑冲效应，并通过中国台湾集集地震的脉冲记录，分析了断层破裂方向和位移大小等震源参数对脉冲强度的影响。此外，基于有限移动源理论，说明了断层辐射与速度脉冲分布的关系，并探讨了利用运动学震源模型研究近断层地震动对速度脉冲影响的技术路线；评述了7种典型的等效速度脉冲模型，建议进一步研究等效速度脉冲函数与震源机制之间的关系。最后，简述了不同类型的断层引起速度脉冲的差异，并推测了产生脉冲型地震动的下限条件，同时展望该研究在地震预警方面的可能性。  相似文献   

基于浅层反射地震勘探技术的大庆地区近地表构造特征研究          下载免费PDF全文

赵斌  刘财  韦庆海  鹿琪  石金虎  余中元  孙海峰 《地球物理学报》2018,61(8):3385-3399

目前，对于大庆地区的地质构造研究成果仅局限在深部构造上，该地区从未开展过针对近地表隐伏断裂的探查工作.本文采用浅层反射地震勘探方法，查明了克山—大安断裂嫩江组以上地层的详细地层信息以及断裂的展布形态；同时，在主干断裂上覆的背斜构造中，发现了许多次级断裂，这些次级断裂在前人的成果中并未提出过，并且在本区的断裂-褶皱构造体系中，次级断裂的活动特性同样受主干断裂活动的影响；然后通过钻孔验证，证实了浅层反射地震勘探结果的可靠性，并且确定了次级断裂的最新活动时代；最后综合编制了松辽盆地长垣隆起地区浅层地质模型，并讨论了本地区的构造体系受晚白垩纪以来太平洋板块俯冲方向变化的影响而形成的构造特征.本次研究中的方法和成果可为大庆市城市发展规划、重大工程建设选址和大庆油田安全高效生产等提供科学依据，可为其他地区开展近地表断裂探查提供借鉴和参考，为本地区浅层地质构造后续研究提供了基础资料，填补该地区近地表地球物理勘探构造研究的空白.  相似文献   

Estimating fractional cover of crop,crop residue,and soil in cropland using broadband remote sensing data and machine learning     

《International Journal of Applied Earth Observation and Geoinformation》2020

The fractional vegetation cover (FVC), crop residue cover (CRC), and bare soil (BS) are three important parameters in vegetation–soil ecosystems, and their correct and timely estimation can improve crop monitoring and environmental monitoring. The triangular space method uses one CRC index and one vegetation index to create a triangular space in which the three vertices represent pure vegetation, crop residue, and bare soil. Subsequently, the CRC, FVC, and BS of mixed remote sensing pixels can be distinguished by their spatial locations in the triangular space. However, soil moisture and crop-residue moisture (SM-CRM) significantly reduce the performance of broadband remote sensing CRC indices and can thus decrease the accuracy of the remote estimation and mapping of CRC, FVC, and BS. This study evaluated the use of broadband remote sensing, the triangular space method, and the random forest (RF) technique to estimate and map the FVC, CRC, and BS of cropland in which SM-CRM changes dramatically. A spectral dataset was obtained using: (1) from a field-based experiment with a field spectrometer; and (2) from a laboratory-based simulation that included four distinct soil types, three types of crop residue (winter-wheat, maize, and rice), one crop (winter wheat), and varying SM-CRM. We trained an RF model [designated the broadband crop-residue index from random forest (CRRF)] that can magnify spectral features of crop residue and soil by using the broadband remote sensing angle indices as input, and uses a moisture-resistant hyperspectral index as the target. The effects of moisture on crop residue and soil were minimized by using the broadband CRRF. Then, the CRRF-NDVI triangular space method was used to estimate and map CRC, FVC, and BS. Our method was validated by using both laboratory- and field-based experiments and Sentinel-2 broadband remote-sensing images. Our results indicate that the CRRF-NDVI triangular space method can reduce the effect of moisture on the broadband remote-sensing of CRC, and may also help to obtain laboratory and field CRC, FVC, and BS. Thus, the proposed method has great potential for application to croplands in which the SM-CRM content changes dramatically.  相似文献   

一种基于GPU和内存映射文件的高分辨率遥感图像快速处理方法     

马秀丹  崔宾阁  钟勇  张永辉  费东 《海洋科学》2018,42(1):139-146

高分辨率遥感图像处理经常面临程序执行时间过长和内存空间不足的问题,虽然并行计算技术可以提高遥感图像的处理速度,但是无法降低算法占用的巨大内存空间。为了解决这一问题,本文提出了一种利用CUDA和内存映射文件的高分辨率遥感图像快速处理方法,并以K-Means算法为例进行了实现。其中,CUDA技术可以有效利用GPU强大的并行计算能力,而内存映射文件技术降低了磁盘I/O速度较慢对算法性能的影响。实验结果表明,本文方法比传统K-Means聚类算法计算速度提高了30倍左右,内存使用量降低了90%以上。  相似文献   

基于遥感水边线的潮滩面积提取方法研究          下载免费PDF全文

张媛媛  高志强  刘向阳  许宁 《海洋开发与管理》2018,35(3):56-61

潮滩作为动态变化的后备土地资源,对其研究具有重要意义。文章以江苏省如东县为研究区,使用环境资源卫星(HJ1A/1B)影像为数据源,应用面向对象技术创建分类规则,实现批量半自动提取水边线,随后利用DSAS软件处理水边线集获得潮位点集,基于最外边界法实现高(低)潮位点的提取,进而获得潮滩范围,估算的如东县潮滩面积为55 182hm~2。最后利用误差矩阵进行精度验证(Kappa系数为0.945)。结果表明:该方法对于潮滩面积提取具有适用性,无论在空间域还是时间域都具有一定的推广性。  相似文献   

Intra-continental deformation and tectonic evolution of the West Junggar Orogenic Belt,Central Asia:Evidence from remote sensing and structural geological analyses     

Wei-Cui Ding  Ting-Dong Li  Xuan-Hua Chen  Jian-Ping Chen  Sheng-Lin Xu  Yi-Ping Zhang  Bing Li  Qiang Yang 《地学前缘(英文版)》2020,(2):651-663

The West Junggar Orogenic Belt(WJOB)in northwestern Xinjiang,China,is located in the core of the western part of the Central Asian Orogenic Belt(CAOB).It has suffered two stage tectonic evolutions in Phanerozoic,before and after the ocean–continental conversion in Late Paleozoic.The later on intracontinental deformation,characterized by the development of the NE-trending West Junggar sinistral strike-slip fault system(WJFS)since Late Carboniferous and Early Permian,and the NW-trending Chingiz-Junggar dextral strike-slip fault(CJF)in Mesozoic and Cenozoic,has an important significance for the tectonic evolution of the WJOB and the CAOB.In this paper,we conduct geometric and kinematic analyses of the WJOB,based on field geological survey and structural interpretation of remote sensing image data.Using some piercing points such as truncated plutons and anticlines,an average magnitude of^73 km for the left-lateral strike-slip is calculated for the Darabut Fault,a major fault of the WJFS.Some partial of the displacement should be accommodated by strike-slip fault-related folds developed during the strike-slip faulting.Circular and curved faults,asymmetrical folds,and irregular contribution of ultramafic bodies,implies potential opposite vertical rotation of the Miao’ergou and the Akebasitao batholiths,resulted from the sinistral strike-slipping along the Darabut Fault.Due to conjugate shearing set of the sinistral WJFS and the dextral CJF since Early Mesozoic,superimposed folds formed with N–S convergence in southwestern part of the WJOB.  相似文献   

Inter-comparison of remote sensing platforms for height estimation of mango and avocado tree crowns     

《International Journal of Applied Earth Observation and Geoinformation》2020

To support the adoption of precision agricultural practices in horticultural tree crops, prior research has investigated the relationship between crop vigour (height, canopy density, health) as measured by remote sensing technologies, to fruit quality, yield and pruning requirements. However, few studies have compared the accuracy of different remote sensing technologies for the estimation of tree height. In this study, we evaluated the accuracy, flexibility, aerial coverage and limitations of five techniques to measure the height of two types of horticultural tree crops, mango and avocado trees. Canopy height estimates from Terrestrial Laser Scanning (TLS) were used as a reference dataset against height estimates from Airborne Laser Scanning (ALS) data, WorldView-3 (WV-3) stereo imagery, Unmanned Aerial Vehicle (UAV) based RGB and multi-spectral imagery, and field measurements. Overall, imagery obtained from the UAV platform were found to provide tree height measurement comparable to that from the TLS (R² = 0.89, RMSE = 0.19 m and rRMSE = 5.37 % for mango trees; R² = 0.81, RMSE = 0.42 m and rRMSE = 4.75 % for avocado trees), although coverage area is limited to 1–10 km² due to battery life and line-of-sight flight regulations. The ALS data also achieved reasonable accuracy for both mango and avocado trees (R² = 0.67, RMSE = 0.24 m and rRMSE = 7.39 % for mango trees; R² = 0.63, RMSE = 0.43 m and rRMSE = 5.04 % for avocado trees), providing both optimal point density and flight altitude, and therefore offers an effective platform for large areas (10 km²–100 km²). However, cost and availability of ALS data is a consideration. WV-3 stereo imagery produced the lowest accuracies for both tree crops (R² = 0.50, RMSE = 0.84 m and rRMSE = 32.64 % for mango trees; R² = 0.45, RMSE = 0.74 m and rRMSE = 8.51 % for avocado trees) when compared to other remote sensing platforms, but may still present a viable option due to cost and commercial availability when large area coverage is required. This research provides industries and growers with valuable information on how to select the most appropriate approach and the optimal parameters for each remote sensing platform to assess canopy height for mango and avocado trees.  相似文献   

基于ShakeMap_CNST的2017年精河6.6级地震灾害快速评估     

刘军  谭明  宋立军  郝婧  毕雪梅  王新刚  常想德 《中国地震》2019,35(2):381-388

基于考虑区域地震动衰减关系、场地效应及震中破裂等多因素的烈度快速评估模型，结合震害预测方法，研发了一套震害预测系统，并以2017年8月9日精河M_S6.6地震的震害预测为例，将对其的预测结果与当前主流系统进行对比。结果表明，采用ShakeMap_CNST系统能对地震的影响范围和烈度进行更为准确的估计，在人员伤亡、受灾人口估计、紧急安置人数及经济损失评估等方面，相对于其他系统，本系统的结果与现场调查的结果更为接近。  相似文献   

Satellite-based monitoring and statistics for raft and cage aquaculture in China’s offshore waters     

《International Journal of Applied Earth Observation and Geoinformation》2020

Based on Landsat 8 remote sensing images, a combination of an unsupervised classification algorithm and artificial review was used to extract areas for Chinese offshore raft and cage aquaculture in 2018. The results of the extraction showed that China’s 2018 coastal zone raft aquaculture area comprised 194,110 ha, of which the province having the largest raft aquaculture area was Jiangsu (28.77 %), followed by Fujian (20.42 %) and Shandong (13.11 %). The cage aquaculture area covered 57,847,799 square meters, of which the provinces with the largest cage aquaculture area were Fujian (64.81 %), Guangdong (17.45 %), and Liaoning (5.63 %). In addition, by combining high-resolution remote sensing image visual interpretation and field investigation, the classification of 1200 sample points in four regions was determined, and the accuracy of the aquaculture area extraction was found to be 87.35 %. The extraction results can be used not only to evaluate China’s aquaculture production but also offer significant reference value for scientific planning related to sea use, ecological environmental protection, and marine disaster prevention and mitigation.  相似文献   

基于FLAC3D数值模拟的清徐地裂缝与交城断裂成因关系研究     

曾金艳  李自红  陈文 《震灾防御技术》2020,15(1):114-122

基于断裂力学理论，应用FLAC3D数值模拟方法对交城断裂活动时附近土体的变形特征进行模拟计算。计算结果表明:断层活动带动上覆土层差异沉降及应力场变化，当断层错动量达到一定程度，断层附近出现拉应力区，土体在拉张应力和自身重力作用下产生垂直差异形变，从而产生地裂缝。将数值模拟结果与方山探槽揭示的地裂缝剖面特征进行对比，二者结果相互印证，说明清徐地裂缝是交城断裂活动的结果，二者具有明显的对应关系，地裂缝为构造成因裂缝。数值模拟结果为研究断裂和地裂缝成因关系提供了佐证。  相似文献