Neotectonic study of Ganga and Yamuna tear faults,NW Himalaya,using remote sensing and GIS

The Ganga and Yamuna rivers emerge from the Himalayas along two major faults known as the Ganga and Yamuna Tear Faults respectively. The two major strike-slip faults transverse to the Siwalik range are clearly seen in satellite imagery of the Dehradun area. Earthquake records, landslide and recent changes in geomorphological features indicate that the area between the Main Boundary Thrust and the Main Frontal Thrust is tectonically active. An effort has been made to study the tectonic evolution and neotectonism of the Ganga and Yamuna tear faults. Spectral and spatial enhancement techniques have been employed to the digital data of IRS-1B LISS-I to delineate the lineaments and major faults of the area. Based on Mohr's theory, failure criteria and statistical analysis of remotely sensed lineament data, horizontal compressive stress values (S_Hmax) have been estimated at various sites of the study area. These data are found to be consistent with the published S_Hmax orientation determined from earthquake focal mechanism solutions. Active faults and lineaments have been extracted from the remotely sensed lineament data. Past earthquake data and depth to basement contour data have been used in an integrated approach with available Geographic Information System (GIS) techniques to reconstruct a present-day regional geodynamic model. Attempts have been made to investigate the genesis of Ganga and Yamuna Tear Faults and possible causes of recent tectonic activities of the area with the help of the proposed geodynamic model.     

Significance of lineament patterns in rock unit classification and designation: a pilot study on the Gharib‐Dara area,northern Eastern Desert,Egypt

Satellite images and aerial photos are among continuous sources of data for mapping lineaments which frequently reflect surfaces of discontinuity in the rocks. The analysis of lineaments not only provides a method for detecting past tectonic trends but also helps in the exploration of minerals, oil and ground water and the seismic risk assessment for nuclear sites and repository studies as well.

In the present study, lineaments have been extracted from the digital satellite scene (Landsat 7, ETM⁺ data) for the Gebel Gharib‐Dara area using GeoAnalyst PCI EASI/PACE software. In a small test area, the lineaments that were digitally extracted for different settings of the GeoAnalyst parameters were compared with the visually interpreted lineaments for optimal settings of the parameters for lineament extraction.

The visual interpretation of the present false colour composite map (FCC) led to tentatively classify the rocks into 24 units to study the spatial distribution of the extracted lineaments. Lineament patterns in the form of lineament azimuth profiles (LAPs) are prepared and they are very characteristic for each unit. The NE lineament trend predominates over all the rock units while the NW trend characterizes those units located towards the Gulf of Suez. LAPs show that the younger granitic rock units of Gebel Gharib, Gebel Abu Khashaba and Gebel Dara (having relatively high radioactivity) are characterized by short amplitude of NW trends relative to the NE trends.

Correlating lineament density maps (LDM) with aeroradiometry total count contour maps and other ground radiometric maps show that rock units with high radioactivity are also characterized by high lineament density and lineament intersection density. Using the same reasoning, new possible uranium targets have been located.

The present study also shows that the younger granitoid is the only rock unit which has been classified into four sub‐lithologic units—G1, G2, G3 and G4—and they probably have a compositional variation that needs further field checking.     

高分辨率遥感影像道路线性要素识别

为有效从高分辨率遥感影像中自动提取道路,提出利用线性要素间的拓扑关系识别道路线性要素的方法。提取影像中的线性要素并获取其邻域的光谱属性形成有向直线段;利用提出的道路线性要素识别模型,将满足条件的有向直线段聚类生成道路要素集;利用先验知识进一步验证。该方法主要使用道路线性要素的结构信息,适用于大范围、场景复杂的遥感影像,具有较高鲁棒性,目前该方法已应用于基于高分辨率遥感影像的GPS导航道路数据的生产和更新。     

The significance of lineaments mapped from remotely sensed images of the 1:250 000 Lau Sheet in the Benue trough of Nigeria

A lineament map of the 1:250000 Lau Sheet in the Benue trough of Nigeria is presented that is derived from LANDSAT and radar images. The two general trends of the lineaments correspond to the structural trend of the Nigerian basement rocks. New lineaments which are probably faults were delineated and recorded along with new circular features, There is a high probability of finding minerals of economic value in the study area, based on the lineament patterns and the tectonic history.     

Application of wavelet analysis to the study of spatial pattern of morphotectonic lineaments in digital terrain models. A case study

Tectonic faults are often associated with characteristic geomorphological features such as linear valleys, ridgelines and slope breaks that can be identified as lineaments in remotely sensed images or digital terrain models. Lineaments of tectonic origin are often characterised by periodicity and characteristic spatial pattern. Unlike traditional methods of autocorrelation, variogram, lineament density and Fourier analysis, wavelet analysis is capable of capturing and describing both periodicity and spatial pattern of lineaments. In this paper, a case study is shown for the application of wavelet analysis to morphotectonic lineament investigation. Results of wavelet analysis are compared to traditional methods. Although this study involves DEM-derived morphological lineaments, the presented wavelet analysis can be also used for lineaments derived from remotely sensed images. These results hold for this case study and provide a good assessment of the relative abilities of wavelet analysis, but it remains to be seen how effective it is for other data sources, areas and geological terrain.     

基于遥感影像的线性构造自动提取

断裂带、断层等地质构造属于地质薄弱区,由于侵蚀等作用会形成线状地貌,表现出线性构造(lineament),可以通过遥感影像上的色调变化进行解译,进而了解断裂的空间展布,推测矿产资源的地下分布、判断地质稳定性。利用线段追踪法(Segment Tracing Algorithm,STA),首先以某一遥感像素为中心分若干个方向在给定大小的搜索窗口内搜索像素值的连续性,然后对连续性好的像素应用地质统计学按一定的阈值判定其是否为线素,再根据像素值在该方向上的变化进行脊谷判定,进而按照一定距离和角度标准把判别为山谷的像素连接成线性构造,最后将重复的线素删除,从而实现遥感影像的线性构造识别。从该方法在个旧锡矿遥感影像(DEM)的应用来看,STA识别的线性构造和实测断裂(层)的走向能较好的吻合,与实测断裂(层)之间的对应关系较好,但在线素连接上需要给定人为设置的参数,还需要进一步改进算法。     

The present state of the remote sensing applications to geological sciences in Greece

This paper describes the Greek University Departments and Government Institutes involved in the remote sensing application to geological sciences. Consequently, it reviews the geological-remote sensing investigations that have been carried out by the researchers of the above Departments/Institutes during the last 10 years

The majority of the Greek geological remote sensing researches have taken place in two remote sensing units, installed in the Institute of Geology and Mineral Exploration (IGME) at Athens and in the Geology and Physical Geography Department, at Aristotle University, Thessaloniki

In the IGME, the research was orientated to map and study lineaments related to faults, geological structure and/or hydrogeology, mineralization, in various areas in Greece, by the use of visual image analysis of LANDSAT (MSS, TM) data and partly by the use of SIR-A data

In the Department of Geology-Physical Geography, the research was firstly orientated to land systems mapping (land classification and land evaluation), delineation of drainage systems, in various Greek territories, by the use of visual image analysis of LANDSAT (MSS, RBV, TM) and SPOT (PA) stereopairs. Recently, the research has been orientated to geomorphological and tectonic (lineaments) mapping because the major structural and geomorphological elements are well displayed on certain digitally enhanced LANDSAT/TM and SPOT/XS, imageries, and partly on SIR-A imageries

The above reconnaissance maps are of considerable interest because they provide the framework for future construction of the same scale (1:250000-1:125 000) various detailed thematic maps (especially in identified critical areas) by geologists, hydrologists, soil scientists, mineralogists, geophycists, seismologists and other geo-scientists.     

An integrated approach to hydro-geological lineament mapping of a semi-arid region of West Africa using Radarsat-1 and GIS

In the 21st century, water resource management will be a major socioeconomic issue and an essential component of progress in semi-arid regions. The Soudano-Sahelian region of Africa suffers from a chronic lack of reliable hydro-geological maps for local water resource managers. To provide better tools for groundwater exploration, this paper focuses on hydro-geological lineament mapping using remote sensing data. The objectives were (1) evaluate the potential of multi-angular and multi-temporal Radarsat-1 images for extracting lineaments in semi-arid regions and (2) provide map of potential hydro-geological lineaments. No significant relationship was found between lineament yield and incidence angle of Radarsat-1 images, while lineament spatial distribution was in good agreement with the land use and geology of the study area. The high scores observed for NNE-SSW and NNW-SSE orientations match the results of local lineament studies of the region. Radarsat-1 image acquired on May 01, 2001 offers the greatest potential, due to the reduced effect of vegetation during this region's dry season. Potential hydro-geological lineaments were mapped using the weighting of well location, presence of green vegetation during the dry season, preferential lineament orientations and presence of cross-points. The mapping revealed five classes (Very low, Low, Moderate, High and Very high) of potential hydro-geological lineaments with high and very high potential poorly represented. Results also reveal that most wells are far enough from lineaments or cross-points and hence the inefficiency of existing drilling programs.     

Fault tectonics of the Shillong plateau and adjoining regions,north-east India using remote sensing data

The Shillong plateau in north-east India shows innumerable fracture lineaments on satellite images. In fact the whole plateau is criss-crossed by fractures. The plateau has been subjected to extensive compressional forces mainly in N-S and E-W directions resulting from the collision of the Indian plate with the Tibetan and Burmese plates, respectively. This type of plate tectonism has been responsible for the formation of many significant faults, folds and other tectonic features in the Shillong plateau and adjoining regions. The well known E-W trending Dauki fault, N-S trending faults, NE-SW trending shear zone and other prominent lineaments and their associated structural features could be studied on the basis of remote sensing techniques. Folding in soft sediments along the Dauki fault reveals the compression direction. Directional compressional tectonism has been expressed through lateral movements along the NE-SW trending shear zone and N-S trending faults and folds in the area just south of the Hatlong thrust. It has been observed from the studies that the Dauki fault zone and the areas in Bangladesh show various tectonic features, which are mostly controlled by vertical movements. Seismicity of the Shillong plateau is quite scattered all over the area. The occurrence of several deep earthquakes (> 1OOkm) indicate deep tectonic activities in the upper mantle. Earthquakes have been found to occur near some faults and this is probably an indication of recent activities along these faults.     

An accuracy assessment methodology for the remotely sensed discontinuities: a case study in Andesite Quarry area,Turkey

The discontinuities play an important role in both the design and development stages of many geotechnical engineering projects. Therefore, semi‐automatic detection of discontinuities based on remote sensing will save a considerable amount of time and cost. Accuracy of the semi‐automatically detected discontinuities is also as important as the detection process, since the results directly reflect the uncertainty in the geotechnical problem. The current paper presents an accuracy assessment methodology for semi‐automatically detected discontinuities from remotely sensed images. Semi‐automatic lineament analysis is performed by using high‐resolution satellite imagery for identification of rock discontinuities at the Andesite quarry area in Gölba??, Ankara, Turkey. A high‐resolution data IKONOS Precision Plus with 1 m resolution orthorectified image has been used in the present study. The accuracy assessment methodology is developed based on a comparison of manually extracted lineaments using directional filtering and semi‐automatically detected lineaments with LINE module of PCI Geomatica 8.2 and manual intervention. The proposed accuracy assessment methodology considers the accuracy based on location and length of the lineaments. In this respect, it has two dimensions. For the algorithm of the developed methodology, a software called LINECOMP, is coded in Java environment. The LINECOMP is composed of three modules. These are: LINE ADDRESS for identification of pixel addresses of lineaments; which is used for locational accuracy assessment; LINE COMPARE for comparing two lineament maps with respect to lineament pixels, which is used for length‐based accuracy; and LINE CLASSIFICATION for classifying the assessed accuracy with respect to the amount of location and length matching. The performance of the proposed accuracy assessment method is also verified by the field studies carried out in the study area.     

Integration of Landsat imagery interpretation and geomagentic data on verification of deep‐seated transverse fault lineaments in SE Zagros,Iran

In this paper, Landsat images are used in the mapping of transverse fault lineaments in Zagros, Iran, and the origin of the fault lineaments as the result of basement reactivation faults is examined using geomagnetic maps. The area under investigation is located in the SE part of the Zagros Fold Belt (ZFB) and was affected by influence of concealed faults, or fault lineaments, during the late Alpine Zagros orogeny. Image interpretation of geological structures such as curvilinear geometry of fold hinges, en echelon pattern of surficial lineaments and younger folds, and breached salt plugs, has been used to map the fault lineaments. Two sets of strike‐lateral transverse fault lineaments have been detected. The first set, NW‐trending, was identified by right lateral curved geometry of the main fold hinges, generation of younger folds, and en echelon pattern of surficial lineaments. The second set, NE‐trending, was verified based on left lateral displacement of the structures and alignment of salt plugs pierced anticline hinges. The placement of Upper Proterozoic salt plugs on the surface along the fault lineaments, together with their correlation with the magnetic‐driven lineaments, implies that the fault lineaments have a basement origin. The trend of these fault lineaments can be correlated with the trend of basement faults in the northern margin of the Arabian plate. The key result of this study is that the fault lineaments identified by integration of remotely sensed data and geomagnetic maps are generated as first order wrench faults by reactivation of the N–S‐trending basement faults. The thick Hormoz Salt formations overlaying the basement do not allow the fault lineaments to emerge at the surface. Therefore, they can be mapped through regional remote sensing and their basement origin can only be recognized by their correlation with magnetic faults. It is also concluded that satellite imagery can greatly contribute to the structural mapping of the ZFB and is therefore a valuable aid for oil and gas exploration in analogous tectonic environments.     

Probabilistic landslide hazard mapping using GIS and remote sensing data at Boun,Korea

The aim of this study is to evaluate the hazard of landslides at Boun, Korea, using a Geographic Information System (GIS) and remote sensing. Landslide locations were identified in the Boun area from interpretation of aerial photographs and field surveys. The topographic, soil, forest, geologic, lineament and land cover data were collected, processed and constructed into a spatial database using GIS and remote sensing data. The factors that influence landslide occurrence, such as slope, aspect and curvature of the topography, were calculated from the topographic database. Texture, material, drainage and effective soil thickness were extracted from the soil database, and type, age, diameter and density of timber were extracted from the forest database. The lithology was extracted from the geological database and lineaments were detected from Indian Remote Sensing (IRS) satellite images. The land cover was classified based on the Landsat Thematic Mapper (TM) satellite image. Landslide hazard areas were analysed and mapped, using the landslide-occurrence factors, by the probability–likelihood ratio method. The results of the analysis were verified using actual landslide location data. The validation results showed satisfactory agreement between the hazard map and the existing data on landslide locations.     

Filtering of satellite images in geological lineament analyses: An application to a fault zone in Central Turkey

Lineament extraction and analysis is one of the routines in mapping large areas using remotely-sensed data, most of which is the satellite images. In this study, we aimed to test different lineament extraction techniques including single band, multiband enhancements and spatial domain filtering techniques. A fast algorithm has been developed for time and cost limited surveys in an area with known dominant and/or any selected orientation of lineaments. During the study for single band analysis, histogram equalization and stretching, for multiband, Principal Components Analysis (PCA) and for spatial domain filtering Prewitt and Sobel filters are utilized. Furthermore, we have developed a new algorithm which consists of a combination of large smoothing filters and gradient filters, in order to get rid of the artificial lineaments which are out of interest and to determine discontinuous and/or closely spaced regional lineaments. The results are as follows; the number of lineaments and their total lengths are 218 285.3 km using the single band; 255 343.9 km in multiband enhancements, and 347644.9 km in the combination of spatial domain filtering including our algorithm. The 59.17 per cent increase in the number of lineaments and the 126.04 per cent increase in the total lengths indicate that a combination of spatial domain filters is the most cost-time efficient algorithm in lineament analyses.     

Evidence of tectonic control of mineralization in Nigeria from lineament density analysis A Landsat-study

Abstract

Lineaments of lengths equal to or greater than 5 km have been interpreted on each of the 30 Landsat frames required to cover the entire area of Nigeria north of 8° latitude. All the spectral bands 4, 5, 6 and 7 were used each at scale 1: 1 000 000. A mosaic of the interpretations from the various scenes was used to prepare a lineament map of Nigeria. Regional analysis of the lineaments based on the spatial and directional attributes of their assemblages suggests general northeast-southwest, northwest-southeast and north-south tectonic trends. The density of lineaments within each 1° × 1° block was determined using the conventional approach and a contour map of lineament densities produced. The lineament density map has been compared with the primary mineral occurrences map of Nigeria adapted from the mineral map of Nigeria. The result shows good correlation between the areas of high lineament density and the areas where the occurrences of most primary minerals such as iron, cassiterite, gold, lead-zinc and uranium have been reported; this correlation suggests that primary mineralization in Nigeria is tectonically controlled. The lineament density map therefore constitutes a useful base map which could aid exploration efforts for solid minerals in Nigeria.     

基于深度学习的遥感图像目标检测技术研究进展

目标检测是遥感图像信息提取领域中的研究热点之一,具有广泛的应用前景。近些年来,深度学习在计算机视觉领域的发展为海量遥感图像信息提取提供了强大的技术支撑,使得遥感图像目标检测的精确度和效率均得到了很大提升。然而,由于遥感图像目标具有多尺度、多种旋转角度、场景复杂等特点,在高质量标记样本有限的情况下,深度学习在遥感图像目标检测应用中仍面临巨大挑战。从尺度不变性、旋转不变性、复杂背景干扰、样本量少和多波段数据检测5个角度出发,总结了近几年基于深度学习的遥感图像目标检测方法。此外,对典型遥感图像目标的检测难点和方法进行分析和总结,并对公开的遥感图像目标检测数据集进行概述。最后阐述了遥感图像目标检测研究的未来趋势。     

New enhancement techniques for azimuthal analysis of lineaments for detecting tectonic trends in and around the Afro-Arabian Shield

The weighted moving average technique is used to analyse lineament azimuths counted by number and length. The technique enhances peak/noise ratio. The quality of distribution is measured by the χ²-test and the degree of correlation between lineament number and length. Moreover, segmenting lineaments improves the enhancement and makes the counting only by number.

Lineament distributions in the four study areas in and around the Afro-Arabian Shield are very similar and can be regarded as a fingerprint. Tentatively, 24 trends are correlated from one area to the other but with varying shape and amplitude. Among these are the Red Sea, Aqaba, Najd, Aden, Meridonial and Trans-Red Sea tectonic trends.

A pattern of lineaments disposed about the N-S is traced in all areas, but in Abha, to the south it deviates 7° to the west. It is related mostly to an old tectonic trend. The deviation might be due to the effect of the rotation of the Arabian Plate counter-clockwise with respect to fixed Africa.     

基于边缘融合的多图像直线提取算法

该文提出了一种新的基于边缘融合的多图像直线提取算法，该算法首先对所有多图像分别提取边缘，然后通过将多图像对应的梯度方向相似的、相邻近的边缘编组，以形成融合的直线支持区域，最后基于最小二乘的方法从直线支持区域拟合出直线段，并提取直线属性．该文提出的算法把边缘的相位信息作为融合要素，能够从复杂的图像中提取出相当低对比度的直线，并且通过分析多图像边缘之间的特性，提出相位压缩和融合编组方案，不仅可以充分融合互补信息还有效降低了算法复杂度．真实的遥感图像直线提取结果表明了该文算法的有效性．     

Remote sensing and river migration in Western India

Abstract

The art of remote sensing has opened up many vistas in the study of river migration as satellite photographs, both in their normal and digitally enhanced modes, vividly show the rivers and their migratory signatures. The rivers migrate for various reasons amongst which tectonic movement is one of the main causes. In the present study an attempt has been made to exhibit the paleochannel network of the rivers of Western India and integrate them with lineament fabric, so as to understand the Quaternary tectonics of the region. The study has shown that Western India shows considerable signs of Quaternary tectonics.     

基于CNN的高分遥感影像深度语义特征提取研究综述

近年来,深度学习作为计算机视觉的研究热点,在诸多方面得以发展与应用。特征提取是理解和分析高分遥感影像的关键基础。为促进高分遥感影像特征提取技术的发展,总结了深度学习模型在高分遥感影像特征提取技术的研究与发展,如:AlexNet,VGG-网和GoogleNet等卷积网络模型在深度语义特征提取中的应用。此外,重点分析和讨论了以卷积神经网络模型为基础的各类深度学习模型在高分遥感影像特征提取方面的应用与创新,如:迁移学习的应用;卷积神经网络(Convolutional Neural Network,CNN)模型结构的改变;CNN模型与其他模型结构的结合等方式,均提升了深度语义特征提取能力。最后,对卷积神经网络模型在高分遥感影像深度语义特征提取方面存在的问题以及后续可能的研究趋势进行了分析。     

Effectiveness of SRTM and ALOS-PALSAR data for identifying morphostructural lineaments in northeastern Brazil

This work provides a comparison between ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band Synthetic Aperture Radar) and DEM (Digital Elevation Model) SRTM (Shuttle Radar Topography Mission) data aiming to evaluate their efficiency to detect morphostructural lineaments. An area in Northeastern Brazil was selected to perform this investigation because of its unambiguous evidence of tectonic fault activity from the Precambrian to the Quaternary. DEM enhanced by shading schemes and palettes was integrated with images representative of morphometric variables as aspect and horizontal curvature in order to enable the recognition of linear features. Images derived from HIS transformation and arithmetic operations of fine beam dual (HH+HV) polarization PALSAR images were processed to provide RGB compositions. Comparisons among lineament maps based on these two remote-sensing products attest to the highest efficacy of SRTM data in detecting geologically meaningful lineaments in the study area. These indicate a main E–W trend and secondary, NE–SW and NW–SE trends, which conform to dominant directions of tectonic fault zones previously mapped in northeastern Brazil. Geomorphological and geological field investigations carried out in the course of the current research further contributed to showing the best performance of this product for unravelling details of three expressive tectonic structures in the study area. This study shows that lineament attenuation in PALSAR images augments proportionally with increased land use. Other important interferences that either rule out or significantly attenuate linear structures are imposed by natural characteristics of the L-band PALSAR sensor, including layover and high-look azimuth in equatorial latitude. The latter might have particularly attenuated detection of lineaments parallel to illumination azimuth. Taking into account these interferences in PALSAR images, integration of DEM-SRTM data used herein offers a much more robust tool to help carry out morphostructural studies in terrains displaying characteristics similar to the ones in the study area.