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1.
In this paper, the satellite geodetic methods are investigated in connection with the movement of tectonic plates. We suggest establishing a combined 3D network for two goals. The first is to study the geoid from the kinematic point of view and vertical datum problems among the Baltic, Adriatic and Black seas. The second is to monitor spatial movements of tectonic plates, especially in the Carpatho-Balkan Region (CBR). 相似文献
2.
The paper is concerned with the problem of adequate mapping of resulting discrete values of the movement velocity as a field. The authors used a statistical method (collocation) to represent measurement results for the Carpatho-Balkan region as a field of recent crustal movement velocity. The collocation method gives a possibility of avoiding a strong influence that the available geomorphological and geological knowledge of the area and individual notions of map-makers have on the drawing of isolines of velocity movements. The new version of the map of recent vertical movements in the Carpatho-Balkan region shows some notable differences from the 1979 version. 相似文献
3.
S. Meier 《Journal of Geodynamics》1987,8(2-4)
The Pannonian Basin or in a broad sense, the Carpatho-Balkan region, is a suitable test area to study the statistical qualities of the Earth's vertical crustal movements. The second-order moments of relative and absolute quantities of motion (vertical velocity, horizontal gradient) are given for the type of a subsiding region with uplifts in its marginal zone — in the ideal case of circular ssymetry. The foundation is the theory of two-dimensional homogenous stochastic processes. Empirically estimated autocovariance functions of the relative vertical rate are approximated by model functions, corresponding to the geotectonic situation of the region, and they are transformed into the wave-number domain. All modelled and empirically estimated second-order moments are given as auxiliary means for signal prediction. The properties of the signal, represented in the maps of the Earth's vertical crustal movements (1:2 500 000, Moscow 1973; 1:2 000 000, Joó et al., 1979), can be derived from the spectral representation. 相似文献
4.
To identify the faults controlling the intensity of recent tectonic processes in the region and to study their geometry and dynamics, one of the variants of the statistical method was used-trend analysis. The map of recent vertical crustal movements in the Carpatho-Balkan region (1:2.000.000) published in Budapest in 1979 was used as initial data for establishing these faults. 相似文献
5.
Tadeusz Wyrzykowski 《Journal of Geodynamics》1987,8(2-4)
A new determination of recent vertical movements of the Earth's crust in Poland is described in this paper. It resulted from the joint adjustment of the network of repeated levelling in 7 countries of Eastern and Central Europe. The author presents the characteristics of the levelling data sets used (measurements made in 1953–1957 and 1974–1979), results of the repeated levelling, the method of determination of the recent crustal movements and of the preparation of the map at a scale of 1:2.500.000 presenting these movements for the area of the whole country. The results of the determination of the Earth's crustal movements are discussed, and causes of the prevailing appearance of sinking movements are suggested. Differences between the values of vertical movements of the Earth's crust obtained during various determinations are presented, as well as the maximum mean error of the difference between new and old determinations. The conformity of these determinations is assessed. 相似文献
6.
In addition to the measurements carried out in the framework of the 1973–1978 international relevellings, further levelling lines have been remeasured on the territory of Czechoslovakia till now. Considering all new relevellings on the region under study, an independent adjustment of annual velocities of vertical movements in whole network was performed. The values of vertical movements were determined relatively to the fundamental benchmark Želešice in the central part of Czechoslovakia, monumented in the bedrock of the southeastern border of the Bohemian Massif. The results are presented in a map of vertical movements and preliminarily interpreted in connection to the geological features of the territory under study. 相似文献
7.
A new map of recent crustal vertical movements (RCVM) in Romania, on the basis of high-precision geodetical measurements by the repeated levelling method, had become necessary firstly as a consequence of the great seismic event of March 4, 1977 with foci under the Vrancea Region (the most important seismic zone in the country) and secondly because many years had passed since the previous edition.Certainly, there are similitudes and differences between the two editions, and the authors will try to put these into evidence and explain them.The general view of the major geological units of Romania in both maps is the same: the mountain regions being zones of more or less continuous uplift, the plains showing subsidence movements and the plateau regions presenting a relative stability. Some modifications became apparent owing to the improvement of the national geodetical network on which the repeated levelling measurements were performed and following the choice of the Harbour of Constanţa as the fundamental point. 相似文献
8.
Jn Vanko 《Journal of Geodynamics》1988,10(2-4)
The first-order relevelling network in Slovakia (International Relevelling Program) was supplemented by second-order relevelling lines measured at the time of the International Relevelling Program (1973–1978) or after its completions, in order to gain more detailed information on the movement activity of the West Carpathians in Slovakia. Mathematical evaluation of relevelling results allowed of drawing a map of recent vertical movements in the region at the scale of 1:1,000,000.The Czechoslovak Uniform Levelling Network of 1947–1962 and the 2nd Czechoslovak Relevelling Network of 1973–1983 constitute the geodetic basis of the map. The relative annual movement velocities, as related to the Initial Fundamental Benchmark Pitelová near Žiar nad Hronom (approximately in the centre of Slovakia) are represented by isolines at intervals of 0.5 mm per year.An analysis of the map 1952–1977 indicates an overall subsidence of lowland regions with respect to the mountanous regions of the West Carpathiams. Central Carpathian morphostructures feature uplifts, with some regions appearing to be stable. Over the entire period under study, the maximal values of vertical movements were + 1.0 mm/year (uplifts) and -4.0 mm (subsidences), the total range being 5 mm/year. 相似文献
9.
The resurvey of both a geodetic network and a levelling net was carried out in June 1981, 8 months after the Ms = 7.3 El Asnam earthquake of 10 October 1980. Previous seismological and neotectonic studies indicate that this event results from a north-east-trending overthrust complex fault of about 40-km length, which shows at least three principal segments with slightly different directions.Vertical movements, evaluated by means of a trigonometric levelling method show an uplift of the thrust fault of about 5 m and a depression of the southeastern edge of about 1 m. These movements are progressively attenuated away from the fault trace (see fig. 1). Horizontal movements have been evaluated by a classical first-order triangulation method. (see fig. 2 and table 1).The resulting mean strain tensors, calculated for different triangles of the geodetic network, indicate a shortening of about 2.50 m which is consistent with the SE-NW direction of compression determined from neotectonic evaluations and focal mechanisms (see fig. 3). Dislocation models are used to explain and discuss the observed deformations in the light of the seismological data and the observed ground breakages. Five segments are required to explain both horizontal and vertical deformations. The magnitude of vertical displacement (about 6 m) at the junction between the southwest and the central segments of the fault argues for the breaking of this area during the main shock and for a slip vector of about 8 m, at least in the central segment.In such circumstances where the first field observations show that a strong coseismic movement has taken place, the best methodology to be used seems to be:
- • - to resurvey as quickly as possible the widest acceptable zone of the old existing geodetic network, without special attention paid to the precision of these measurements.
- • - to set up as soon as possible a small aperture geodetic network of high accuracy in order to monitor the possible postseismic readjustments.
10.
Recently, intensive investigations were carried out in Hungary to explore the characteristics of vertical crustal movements. In the first phase (by using repeated geodetic measurements) vertical movement velocities were mapped. In the second phase the aim was to study the movement tendencies in more detail. In the professional literature many mathematical methods are reported. Among these the method of horizontal gradients is applied quite often. In this paper the velocity function of the vertical movements is represented by polynomials and the gradient values are computed from these. To control the values calculated from the velocity functions they were compared to the observed values. The above method was applied to the whole territory of Hungary and also to four zones individually. These zones were determined on the basis of geological information. Besides a short review of the method we present the results: velocity functions, gradients and control data. The gradient vectors are also presented in graphical form. 相似文献
11.
Marino Martini Luciano Giannini Antonella Buccianti Franco Prati Paola Cellini Legittimo Paolo Iozzelli Bruno Capaccioni 《Journal of Volcanology and Geothermal Research》1991,48(1-2)
A systematic geochemical investigation on the thermal manifestations of the volcanic area of Phlegrean Fields started in 1980, with the aim of obtaining useful information about the changes possibly occurring at the same time of vertical ground movements, termed as “bradyseismic”, which frequently interested this area.The attention was initially given to the fumaroles and the boiling pools of Solfatara and Pisciarelli, then subsequently extended to thermal springs, dug wells, and crater lakes.Analytical data pertaining to a period preceding the last crisis of 1982–1984 were then available, as well as other data collected during the previous crisis of 1970; a comprehensive picture of the variations observed before, during and after the acceleration of vertical movement has been drawn.According to the results obtained, the intrusion of a magmatic body as the trigger of the observed ground deformation is considered unrealistic. The whole area appears now in a quiet stage, and no further perturbation is expected without previous significant tectonic activity; chemical precursors appear suitable for an early detection of changes occurring at depth, to forecast possible consequences to be expected in the surface environment. 相似文献
12.
In Hungary four extensometric observatories were established in the last two decades. The extensometers were installed primarily for observations of Earth tides. A 15-year continuous data series (1991–2005) was recorded at the Sopronbánfalva station and a 7-year record (1993–1999) was obtained at the Pécs station. The length of the measured continuous data series at the two other stations (Bakonya and Budapest) is only a few years. The long-term data records were also applied to the investigation of long-periodic deformations caused by recent tectonic movements. To get an insight into the present day tectonic processes on the margin of the Pannonian Basin, the measurement results of two additional stations (Vyhne in Slovakia and Beregovo in Ukraine) were also included into the investigations. The seasonal variations in the long data series due to temperature and air pressure effects were eliminated. The residual curve – after the correction of the seasonal effects and filtering the “high frequency” components (e.g. earthquakes, Earth tides, etc.) – contains the instrumental drift. It is impossible to determine this curve mathematically. It can be diminished by special instrumental solutions and by regular calibration of the instruments. This paper shows methods and possible solutions how the instrumental drift was investigated and eliminated in order to get the most reliable data for studying recent tectonic movements. The reliability of the extensometric measurements was tested by the tidal evaluation of the data series. The results of the observations show that the Pannonian Basin is under compressive stress. The strain rates measured by extensometers on the margin of the basin are about three orders of magnitude higher than the intra-plate strains obtained by GPS measurements. The reason for this large difference arises from the interaction between the plate boundary and intra-plate forces and from the different measurement techniques. Investigations showed that the rate of the tectonic movements varies, and depends on the local geographical and topographical conditions. 相似文献
13.
The aim of this work is the evaluation of the vulnerability of landslides in static, pseudostatic and dynamic conditions, to produce slope instability maps. A deterministic approach, using a GIS, (ILWIS 1.4 — The Integrated Land and Water Information System User's Manual, Enschede, 1993, The Netherlands) is presented. The analysis in static and pseudostatic conditions, using the infinite slope: analysis and the ordinary slice method, is carried out and the values of Fs (factor of safety) and Kc (coefficient of critical horizontal acceleration) are evaluated; the analysis in dynamic condition is performed, using Newmark's method, (Geotechnique, 1965, 23, 139-60), and the value of the final displacement during the application of an accelerogram is calculated. The applied methodologies and the results for the area corresponding to the NE sector of the 1:50.000 “Fabriano” (Marche Region, Italy) geological map sheet, are presented. 相似文献
14.
近20年来河西-祁连山东部地区三条规模较大的北东向构造带在区域垂直形变图上反映明显。因受区域应力场强度的控制,其垂直形变表现出随时间波浪状演化式。区域垂直形变图像与莫霍面等深线相似,说明这几条北东向构造带的深部成因机制。它们对区内的中强地震起着很强的控制作用,与北西西及北北西向断裂构造共同构成了本区的控震构造网络。 相似文献
15.
A. Boud 《Journal of Geodynamics》1987,7(3-4)
Interdisciplinary interpretation of satellite and geologic-geophysical data can be applied to East Africa as a cost-effective means of regional tectonic evaluation. All available data sources: geologic and geophysical maps and remote sensing images should be used. Remote sensing methods are very efficient for the “synoptic overlook” necessary to pinpoint areas for more detailed investigation.The use of satellite imagery is a way of applying and testing structural frameworks for mineral potential as surface reflections of deep tectonic features can be recognized. Mineralization can be correlated with tectonic lineaments that are probably related to persistent discontinuities in the upper mantle. The outlining of these discontinuities would be of value in the search for the understanding of riftogenesis and in the search for mineralization.This paper is a review of such work with a specific example from Canada, and how the approach can be applied to Africa for continuing research on recent crustal movements. 相似文献
16.
A.R. Mazaheri B. Zerai G. Ahmadi J.R. Kadambi B.Z. Saylor M. Oliver G.S. Bromhal D.H. Smith 《Advances in water resources》2005,28(12):1267-1279
For single-phase flow through a network model of a porous medium, we report (1) solutions of the Navier–Stokes equation for the flow, (2) micro-particle imaging velocimetry (PIV) measurements of local flow velocity vectors in the “pores throats” and “pore bodies,” and (3) comparisons of the computed and measured velocity vectors. A “two-dimensional” network of cylindrical pores and parallelepiped connecting throats was constructed and used for the measurements. All pore bodies had the same dimensions, but three-different (square cross-section) pore-throat sizes were randomly distributed throughout the network. An unstructured computational grid for flow through an identical network was developed and used to compute the local pressure gradients and flow vectors for several different (macroscopic) flow rates. Numerical solution results were compared with the experimental data, and good agreement was found. Cross-over from Darcy flow to inertial flow was observed in the computational results, and the permeability and inertia coefficients of the network were estimated. The development of inertial flow was seen as a “two-step” process: (1) recirculation zones appeared in more and more pore bodies as the flow rate was increased, and (2) the strengths of individual recirculation zones increased with flow rate. Because each pore-throat and pore-body dimension is known, in this approach an experimental (and/or computed) local Reynolds number is known for every location in the porous medium at which the velocity has been measured (and/or computed). 相似文献
17.
Vertical oscillating movements of the Earth's crust on continents have occurred and are occurring everywhere on the Earth's surface, continuously throughout the entire geological history of the Earth. This provides grounds to consider them as the basic type of tectonic movements, which form the general background of the tectogenetic process, on which locally, and only at separate moments of time, other tectonic movements and deformations appear.According to the time of occurrence, the vertical movements are divided into recent, young, modern, and ancient. In compliance with this subdivision, different methods are applied to define and study the movements. The major characteristic of the vertical movements is their rhythm, or periodic change in sign of movement, which caused them to be calledoscillating. Rhythms of movements are of several orders. The largest rhythms, which comprise tectonic cycles, are manifested on a global scale; smaller rhythms have a local distribution. It is significant that, in the beginning and in the end of each tectonic cycle, an increase of intensity and contrast of movements is observed, no matter in which region or regime, whether stable or mobile, it occurs. 相似文献
18.
Transformation between gravimetric and GPS/levelling-derived geoids using additional gravity information 总被引：1，自引：0，他引：1
The transformation from the gravimetric to the GPS/levelling-derived geoid using additional gravity information for the covariance function of geoid height differences has been investigated in a test area in south-western Canada. A “corrector surface” model, which accounts for datum inconsistencies, long-wavelength geoid errors, vertical network distortions and GPS errors, has been constructed using least-squares collocation. The local covariance function of geoid height differences is usually obtained from residual values between the GPS/levelling and gravimetric geoid heights after the elimination of all known systematic distortions. If additional gravity data (in the form of gravity anomalies) are available, the covariance function of geoid height differences can be determined by the following steps: (1) transforming the GPS/levelling-derived geoid heights into gravity anomalies; (2) forming differences between the computed in step 1 and given gravity anomalies; (3) determining the parameters of the local covariance function of the gravity anomaly differences; (4) constructing an analytical covariance model for the geoid height differences from the covariance function of the gravity anomaly differences using the parameters derived in step 3. The advantage of the proposed method stems from the great number of gravity data used to derive the empirical covariance function. A comparison with the least-squares adjustment shows that the standard deviation of the residuals of the predicted geoid height differences with respect to the control point values decreases by 2.4 cm. 相似文献
19.
以1995—2016年川滇地区实测水准资料为例,分别采用动态经典平差、拟稳平差、伪逆平差和GPS速率约束平差4种平差方法进行平差计算,分析探讨4种平差方法在水准网平差处理时的适用条件及优缺点;最后分析了1995—2016年川滇地区的地壳垂直形变特征。结果表明:①在条件具备的情况下,GPS速率约束平差优于动态经典平差、拟稳平差和伪逆平差,主要体现在GPS速率可知、平差后速率误差明显减小,且能有效地抑制误差的传播与积累;而拟稳平差、伪逆平差虽优于动态经典平差,但同样存在着基准假定的问题;②1995—2016年川滇地区整体处于差异隆升阶段,只有四川盆地、滇西北和滇南少部分区域下沉,跨断裂剖面结果显示几条断裂带以继承性运动为主。 相似文献
20.
P. Brotzu M. T. Ganzerli-Valentini L. Morbidelli E. M. Piccirillo R. Stella G. Traversa 《Journal of Volcanology and Geothermal Research》1981,10(4):365-382
The different basalt types related to rift structure development have been investigated, starting from the pre-rift stage in the northern Ethiopian rift and its eastern escarpment and plateau.The basic volcanic rocks are represented mainly by transitional basalts, both in the pre-rift (plateau) and rift (escarpment and rift floor) stages. A striking feature is that although the plateau basalts show clear tholeiitic affinity and the rift basalts reveal a somewhat pronounced “alkaline” character, the REE and LILE element abundances, however, progressively decrease from the “tholeiitic” basalts of the plateau to the “alkaline” basalts of the rift.All data support the view that such contrasting features may be attributed to a continuous depletion of hygromagmatophile (REE, LILE) elements in the mantle source material, related to the large volumes of magmas produced in the early phase of rift structure development. The transition from “tholeiitic” (plateau) to “alkaline” (rift) transitional basalts is related to decreasing intensity of extensional movements. 相似文献