利用InSAR资料反演2008年西藏改则MW6.4和MW5.9地震的断层参数

2008年1月9日在我国西藏改则发生了一次M_W6.4地震,随后有40次3.5级以上余震发生,其中最大的一次为1月16日的M_W5.9余震.本文处理了ENVISAT ASAR两轨（升轨和降轨）同震资料,精确确定了同震地表位移的空间分布;随后利用弹性半空间的位错模拟确定了上述事件的断层面参数;最后,基于非均匀滑动模型反演确定了两次地震断面上的滑动分布.结果表明,M_W6.4主震断层为走向218°、倾角52°的西倾断层,最大滑动量约1.9 m,出现在地表以下约7.6 km处;而M_W5.9余震发生在主震断层西3.2 km的地方,发震断层为走向200°、倾角59°的西倾断层,最大滑动量约1.0 m,出现在地表以下约3.9 km处.     

顾及矢量特征的机载LiDAR点云数据压缩方法

LiDAR技术可获取海量点云数据,数据压缩是点云数据预处理的一个重要环节。该文结合大范围城市区域高程范围随区域变化大的特点,提出一种有效的压缩策略。该策略主要通过建立高程方向不均等的三维格网来提高邻域点集的搜索效率,并根据某一压缩准则计算特征量对数据进行压缩。将该策略应用于上海浦东某区域,并与均匀采样法进行比较,证明其能有效提高点云数据压缩效率。     

基于捷联惯导的航空矢量重力测量的降阶滤波算法

捷联惯导系统(SINS)在航空矢量重力测量中的基本功能是比力测量,但是纯惯导不能满足精度要求,因此通常采用卡尔曼滤波SINS/DGPS组合导航来提高比力测量的精度。通过误差状态可观性分析设计一种新的降阶滤波算法,该算法使得比力测量分系统的概念更加明晰,并通过仿真验证新算法的正确性。     

干涉合成孔径雷达及其在火山研究中的应用(第一部分:InSAR原理)

干涉合成孔径雷达是一项能够对地表变形进行测量的遥感技术,在一个巨大区域内,它的变形测量精度可达亚厘米级,而其空间分辨率则在数十米以内。本文回顾了InSAR技术的基本理论,阐明了它的工作原理,并对应用InSAR技术进行地表变形测量的相关问题进行了讨论。     

机载合成孔径雷达影像与航片判绘的对比研究

遥感影像判绘是提取影像上有用地物信息的一种基本方法。本文分别介绍了航空摄影像片和机载合成孔径雷达影像判绘的主要内容。并利用同一地区大致同一时相的航片和机载SAR影像分别进行了判绘,比较分析了两类影像资料用于判绘的各自特点。     

航空电磁技术在冻土调查中的探测能力分析

准确评估冻土三维分布和阶段性变化对我国气候、水资源、生态、工程建设等方面具有重要意义.我国多年冻土大多分布在高海拔地区,利用地面物探确定多年冻土厚度具有效率低、成本高、交通不便等问题,而依据电阻率差异的航空电磁技术具有较大优势.根据青海祁连地区冻土厚度、电阻率等信息构建地电模型,并针对Aer-oTEM时间域航空电磁系统...     

固定翼时间域航空电磁系统的飞机选型问题

对国外典型固定翼时间域航空电磁系统飞机平台及国产飞机平台的各项性能进行了对比分析,对改装能力、运行费用、安全性等几个方面进行了评价,总结了固定翼时间域航空电磁系统设计飞机选型的基本经验和规律,提出了用综合效费比指标来指导飞机选型工作。     

国外航空地球物理试验场建设启示

在国家863重大计划项目的支持下,开展了我国航空地球物理试验场建设和研究工作。为此,开展了对国外航空地球物理试验场建设情况的调研,详细总结了加拿大安大略湖Reid-Mahaffy航空电磁地球物理试验场选场条件、建设方案以及试验场应用等情况,为我国航空地球物理试验场建设提供了重要启示。     

Quantification of permafrost creep provides kinematic evidence for classifying a puzzling periglacial landform

Mechanical processes operating on the slope surface or at depth control the dynamics of alpine landforms and hold critical information of their geomorphological characteristics, yet they often lack systematic quantification and in-depth interpretation. This study aims to address a long-standing issue concerning geomorphological classification from a kinematic perspective. A group of periglacial landforms consisting of several lobes were discovered in the East Kunlun Mountains of China 30 years ago but were ambiguously classified as rock glaciers and later as gelifluction deposits. Here, we use satellite Interferometric Synthetic Aperture Radar to quantitatively characterize the spatial and temporal changes of the surface movement of these landforms. We observe that: (1) its 17 lobes show a pattern of landform-scale and uniform surface movement, especially during May to October; (2) the lobes move at a spatial mean downslope velocity of 10 to 60 cm/yr and a maximum velocity as high as 100 cm/yr in summer; (3) the landforms are nearly inactive from winter to late spring. Based on these observations, we postulate that the movement of the lobes are driven by deep-seated permafrost creep which typically occurs in rock glaciers. The debris of Lobe No.4 is composed of both boulders and pebbles supported by fine-grained matrix generated from the in situ weathering process. It develops a talus-like oversteepened front around 40° and a convex transverse profile perpendicular to the creep direction, which are also characteristic features of a rock glacier. Piecing these observations together, we identify Lobe No.4 as a debris-mantled-slope-connected rock glacier, with the gelifluction process occurring on the surface as small-scale and discrete events. © 2020 John Wiley & Sons, Ltd.     

Spatial and temporal variations in subsidence due to the natural consolidation and compaction of sediment in the yellow river delta,china

ABSTRACT

The Yellow River Delta, which is the second-largest delta in China, has experienced varying degrees of land subsidence since the late 1970s. Although recent studies have identified the natural consolidation and compaction of sediment among the most important contributors to geologic processes, their processes have rarely been quantified. We estimated the sediment compaction over different time ranges to determine the temporal evolution of subsidence parameters (i.e., cumulative compaction). Estimates of primary consolidation, secondary consolidation, and the degree of consolidation in 152 boreholes revealed the spatial–temporal characteristics of sediment compaction and consolidation using geotechnical parameters collected from 152 boreholes, soil mechanics equations and the Kriging interplolation method. In addition, these estimates were partially constrained and cross-validated using the interferometric synthetic aperture radar (InSAR) results from early 2007 to late 2010 which were provided in a previous study. By performing a comparison analysis between theoretical evaluations of compaction for borehole data and InSAR observations, we were able to quantify subsidence due to sediment compaction. The comparison results suggest that the theoretical solutions agreed well with the measurements recorded by the well-validated, advanced InSAR method and that the deviations between the InSAR technique and geotechnical evaluations ranged from ?22 to 3?mm. The results reveal that the land subsidence of the chosen borehole sites during the investigative period was dominated by the primary consolidation and compaction of sediment. The underprediction of subsidence may be explained by fluid withdrawal, oil exploitation and engineering construction. To speculate, more geological disasters may occur if the current subsidence condition extends into the future.