Very high electrical conductivity beneath the Münchberg Gneiss area in Southern Germany: implications for horizontal transport along shear planes   总被引：1，自引：0，他引：1  

Oliver Ritter  Volker Haak  Volker Rath  Eckardt Stein  & Manfred Stiller 《Geophysical Journal International》1999,139(1):161-170

New magnetotelluric data from the Münchberg Gneiss complex in Southern Germany reveal a zone of extremely high electrical conductivity. 1-D modelling of the data is justified in the period range 0.01 to 10  s. At least three layers are required to explain the steepness of the apparent resistivity curves, and the best-fitting models comprise four layers with successively higher conductivities. The layers of highest conductivity at depths between 2.2 and 3.6  km correlate with pronounced bands of high seismic reflectivity (profile DEKORP 85-4N). The Münchberg complex is today widely recognized as a tectonic klippe, consisting of rocks whose metamorphic and stratigraphic order is inverted rather than overturned. The material was transported into its present position by predominantly horizontal tectonic forces along shear zones. We interpret the high conductivity and high reflectivity as remnants of this transport process.  相似文献   

Digital elevation models derived from airborne laser scanning point clouds: appropriate spatial resolutions for multi‐temporal characterization and quantification of geomorphological processes          下载免费PDF全文

Rudolf Sailer  Martin Rutzinger  Lorenzo Rieg  Volker Wichmann 《地球表面变化过程与地形》2014,39(2):272-284

Digital terrain models (DTMs) are a standard data source for a variety of applications. DTM differencing is also widely used for detection and quantification of topographic changes. While several investigations have been made on the accuracy of DTMs, calculated from different kinds of input data, little has been published on the error of DTM differencing, specifically for the quantification of geomorphological processes. In this study, an extensive, multi‐temporal set of airborne laser scanning (ALS) data is used to investigate the accuracy of topographic change calculations in a high alpine environment, caused by different geomorphic processes. Differences from DTMs with cell sizes ranging from 0.25 m to 10 m were calculated and compared to very accurate point‐to‐point calculations for a variety of processes and in nearby stable areas which show no significant surface changes. The representativeness of the DTM differences is then compared to the terrain slope and surface roughness of the investigated areas to show the influence of these parameters on the errors in the differences. Those errors are then taken into account for analyses of the applicability of different cell sizes for the investigation of geomorphic processes with different magnitudes and over different time periods. The analyses show that the error of DTM differences increases with lower point densities and higher roughness and slope values. The higher the error, the greater the differences between two elevation datasets have to be in order to quantify certain morphodynamic processes. Lower point densities and higher roughness and slope values require greater process rates or longer time intervals in order to obtain valid results. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

From new political organizations to changing moral geographies: Unpacking global civil society     

Volker Heins 《GeoJournal》2000,52(1):37-44

The discourse of globalization suggests that territorial and cultural boundaries are increasingly insignificant or even disappearing in today's `world of flows'. More recently, this notion of borderlessness has also suffused broad reaches of the imagination of policy-makers and social scientists in the Western world. Thus, the term `global civil society' was coined to capture the experience and impact of transnational environmental and human rights activism. In this paper, however, it is argued that the concept remains both undertheorized and empirically dubious. In order to analytically `unpack' the concept, I provide a brief summary of an empirical research project on networks of new political organizations in South Asia and the West. The evidence assembled suggests the need to reconceptualize the geographies of transborder solidarity and concern beyond the rhetoric of global civil society.  相似文献   

Twenty years of soil erosion on-farm measurement: Annual variation,spatial distribution and the impact of conservation programmes for soil loss rates in Switzerland     

Volker Prasuhn 《地球表面变化过程与地形》2020,45(7):1539-1554

Long-term field assessments of soil erosion on the landscape scale are very scarce. Such monitoring programmes create sound data regarding severity, extent, frequency and types of soil erosion and the vulnerability of particular crops. In a 20-year monitoring programme between 1997 and 2017, accurate erosion damage mapping was carried out on 203 fields on arable land in the Canton of Berne (Switzerland). During 115 field inspections, 4060 field years and 2165 mapped erosion systems were recorded. Because several soil conservation programmes were implemented during this period, two 10-year time periods (1st October 1997 to 30th September 2007 [P1] and 1st October 2007 to 30th September 2017 [P2]) were established and compared. The soil erosion rate was already low in P1 (mean: 0.74 t ha⁻¹ year⁻¹), but decreased significantly in P2 (mean: 0.20 t ha⁻¹ year⁻¹). During P1 and P2, respectively, 12 and 42% of the fields were without any visible erosion. Within 10 years, erosion occurred on each field on average 3.2 times in P1 and only 1.3 times in P2. Soil losses are spatially concentrated and linked to topographically defined pathways (thalwegs, slope depressions) or human-made flow pathways (wheel tracks, tramlines, headlands). Financial incentives, rising awareness among farmers, innovative contractor farmers and good extension service of cantonal agencies helped conserve 85% of the arable land in the study area with conservation tillage methods by 2015. As a result, soil erosion was significantly reduced. The field-based measurements show that a significant decrease in soil erosion is possible by changes in soil tillage practices and that erosion control is feasible almost everywhere under real-life conditions on farmers’ fields. In this respect, the Frienisberg region is a case example of successful erosion control. © 2020 John Wiley & Sons, Ltd.  相似文献   

Jonathan Allday: Quarks,Leptons and the Big Bang. Institut of Physics Publishing,Bristol and Philadelphia 1998, XI + 315 Seiten ISBN 0–7503–0461–8, Preis: $ 98.00     

Volker Müller 《Astronomische Nachrichten》1998,319(6):374-374

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Research and Application of In‐seam Seismic Survey Technology for Disaster‐causing Potential Geology Anomalous Body in Coal Seam     

TENG Jiwen  LI Songying  JIA Mingkui  LIAN Jie  LIU Honglei  LIU Guodong  WANG Wei  Volker SCH?PE  FENG Lei  YAO Xiaoshuai  WANG Kang  YAN Yafen  ZHANG Wanpeng 《《地质学报》英文版》2020,94(1):10-26

In order to effectively detect potential geology anomalous bodies in coal bearing formation, such as coal seam thickness variation, small faults, goafs and collapse columns, and provide scientific guidance for safe and efficient mining, the SUMMIT-II EX explosion-proof seismic slot wave instrument, produced by German DMT Company, was used to detect the underground channel wave with the help of transmission method, reflection method and transflective method. Region area detection experiment in mining face had been carried out thanks to the advantage of channel wave, such as its great dispersion, abundant geology information, strong anti-interference ability and long-distance detecting. The experimental results showed that: (1) Coal seam thickness variation in extremely unstable coal seam has been quantitatively interpreted with an accuracy of more than 80% generally; (2) The faults, goafs and collapse columns could be detected and predicted accurately; (3) Experimental detection of gas enrichment areas, stress concentration regions and water inrush risk zone has been collated; (4) A research system of disaster-causing geology anomalous body detection by in-seam seismic survey has been built, valuable and innovative achievements have been got. Series of innovation obtained for the first time in this study indicated that it was more effective to detect disaster-causing potential geology anomalies by in-seam seismic survey than by ground seismic survey. It had significant scientific value and application prospect under complex coal seam conditions.  相似文献   

R. RUFFINI (ed.): Proceedings of the Fourth Marcel Grossmann Meeting on General Relativity. North-Holland,Amsterdam 1986 (USA und Kanada: Elsevier,New York). L + 1862 Seiten. Preis: Dfl. 420.00. ISBN: 0-444-87030-X     

Volker Müller 《Astronomische Nachrichten》1988,309(4):248-248

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Vertical mixing in the Baltic Sea and consequences for eutrophication - A review   总被引：1，自引：0，他引：1  

Jan Hinrich Reissmann  Hans Burchard  Rainer Feistel  Eberhard Hagen  Hans Ulrich Lass  Volker Mohrholz  Günther Nausch  Lars Umlauf  Gunda Wieczorek 《Progress in Oceanography》2009,82(1):47-80

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Annual deformation signals from homogeneously reprocessed VLBI and GPS height time series   总被引：3，自引：3，他引：0  

Volker Tesmer  Peter Steigenberger  Markus Rothacher  Johannes Boehm  Barbara Meisel 《Journal of Geodesy》2009,83(10):973-988

The first part of this paper compares homogeneously reprocessed Very Long Baseline Interferometry (VLBI) and Global Positioning System (GPS) long-term height series from 1994 to 2007. The data analysis used fully adapted state-of-the-art models (like VMF1 and a priori zenith delays from ECMWF) for the GPS and VLBI processing. The series are compared in terms of long-term non-linear behaviour, harmonic and mean annual signals (not necessarily of harmonic nature). The similarity between both techniques is very good (especially the mean annual signals), which is assumed to be due to the adapted models and consistent reprocessing of both series. As two almost independent observing techniques see the same annually recurring signals at almost all co-located sites, we expect a good geophysical interpretability as integral vertical deformation. For the second part of this paper, the height time series of 161 suitable GPS sites (of the same solution as before) are used to determine a harmonic and a mean annual signal for each of them. Comparing the annual signals for this big dataset visually to GRACE-determined load deformations described in other publications, we find good agreement. This puts emphasis to the assumption that our height data have a lot of potential to be interpreted as geophysical signals. Out of these 161, 131 are grouped to 55 clusters, if at least two nearby (some thousand kilometres) sites show similar mean annual signals, which are thus confirmed to be real regional deformation, not local or technical artefacts. These 55 signals are presented on a “world map” of regional average mean annual height signals, as easy-to-handle tool to validate geophysical models. The data of these measured regional mean annual signals can be downloaded from a web-page for numerical analysis.  相似文献   

Middle to Late Pleistocene lake‐level fluctuations of Lake El'gygytgyn,far‐east Russian Arctic     

Grigory Fedorov  Andrei A. Andreev  Elena Raschke  Volker Wennrich  Georg Schwamborn  Olga Y. Glushkova  Olaf Juschus  Anja Zander  Martin Melles 《Boreas: An International Journal of Quaternary Research》2019,48(2):516-533

Lake El'gygytgyn, located in central Chukotka, Russian Arctic, was the subject of an international drilling project that resulted in the recovery of the longest continuous palaeoclimatic and palaeoenvironmental record for the terrestrial Arctic covering the last 3.6 million years. Here, we present the reconstruction of the lake‐level fluctuations of Lake El'gygytgyn since Marine Isotope Stage (MIS) 7 based on lithological and palynological as well as chronological studies of shallow‐water sediment cores and subaerial lake terraces. Reconstructed lake levels show an abrupt rise during glacial–interglacial terminations (MIS 6/5 and MIS 2/1) and during the MIS 4/3 stadial–interstadial transition. The most prominent lowstands occurred during glacial periods associated with a permanent lake‐ice cover (namely MIS 6, MIS 4 and MIS 2). Major triggering mechanisms of the lake‐level fluctuations at Lake El'gygytgyn are predominantly changes in air temperature and precipitation. Regional summer temperatures control the volume of meltwater supply as well as the duration of the lake‐ice cover (permanent or seasonal). The duration of the lake‐ice cover, in turn, enables or hampers near‐shore sediment transport, thus leading to long‐term lake‐level oscillations on glacial–interglacial time scales by blocking or opening the lake outflow, respectively. During periods of seasonal ice cover the lake level was additionally influenced by changes in precipitation. The discovered mechanism of climatologically driven level fluctuations of Lake El'gygytgyn are probably valid for large hydrologically open lakes in the Arctic in general, thus helping to understand arctic palaeohydrology and providing missing information for climate modelling.  相似文献