A combined study of macroseismic data and focal mechanisms applied to the West-Bohemian earthquake,Czechoslovakia     

J. Zahradník  M. Antonini  G. Grünthal  J. Janský  D. Procházková  E. Schmedes  A. Špičak  J. Zedník 《Pure and Applied Geophysics》1990,133(1):53-71

The main shock of the West-Bohemian earthquake swarm, Czechoslovakia, (magnitudem=4.5, depthh=10 km) exhibits an irregular areal distribution of macroseismic intensities 6° to 7° MSK-64. Four lobes of the 6° isoseismal are found and the maximum observed intensity is located at a distance of 8 km from the instrumentally determined epicentre. This distribution can be explained by the energy flux of the directS wave generated by a circular source, the hypocentral location and focal mechanism of which are taken from independent instrumental studies. The theoretical intensity, which is assumed to be logarithmically proportional to the integrated squared ground-motion velocity (i.e.,I=const+log v ² (t)dt), fits the observed intensity with an overall root-mean-square error less than 0.5°. It is important that the present intensity data can also be equally well explained by the isotropic source. The fit was attained by means of a horizontally layered model though large fault zones and an extended sedimentary basin suggest a significant lateral heterogeneity of the epicentral region. The results encourage a broader application of the simple modelling technique used.  相似文献   

On the formation mode of the Guleman chromite deposits (Turkey)     

Ş. Üşümezsoy 《Mineralium Deposita》1990,25(2):89-95

Kefdag and Soridag chromite pods occur in upper mantle residual peridotites, which consist of harzburgite and dunites. The peridotites represent the residual of multistage, depleted upper-mantle peridotites. The chromitite bodies were formed during the uprising of chromium-rich picritic melts, through the residual upper mantle diapir, along the magma conduits. Chromitite grains were deposited in the caves of the magma conduits under the control of the convection currents.  相似文献   

Observations of coronal polarization at the solar eclipse of 7 March, 1970     

J. Dürst 《Solar physics》1976,50(2):457-464

Polarigraphic observations of the 7 March, 1970 eclipse were made at Miahuatlán (Mexico) with a camera of 120 cm focal length. A polarizing filter in front of the objective could be adjusted at 8 different positions, 22.5° apart. Reduction of eight photographs of the white light corona yields polarization at 72 position angles and from r = 1.1 up to 2.1. High polarization which cannot be explained with Thomson scattering was not observed. An analysation of the measuring accuracy shows, that it is not possible to determine exactly the direction of polarization in the outer corona with the classical method of measuring polarization with a small number of photographs. The coronal hole in the south-west quadrant is analysed. The low intensity and polarization can be explained by a hole with an extent in longitude between 1 and 2 times its extent in latitude and with a minimum electron density between 0 and 0.3 of that outside the hole.Astronomische Mitteilungen der Eidgenössischen Sternwarte Zürich, No. 347.  相似文献   

Mass-luminosity distribution and physical conditions of ionized gas in NGC 4575     

M. Pastoriza  E. L. Agüero 《Astrophysics and Space Science》1976,39(1):201-211

Photographic photometry and spectroscopic observations of NGC 4575 suggest it to be a galaxy of reduced dimensionsD×d=14.4×13.5 kpc and of high luminosityM=–20.7. The rotation curve was also determined. Assuming a model of three homogeneous similar spheroids, we derived the density and mass distribution, and their total mass was found to be _T =2.33 × 10¹⁰.The mass luminosity ratio does not vary withinr=24, indicating that the stellar composition is similar within it, and the ratio _T / _T 1 suggests that this object contains a high proportion of young stars. From the emission lines it is found that the electronic density Ne100 cm^–3 is relatively low in the HII regions. The abundance ratiosN(N)/N(S) andN(N)/N(H) for the nucleus and two emission regions were also derived.  相似文献   

On the structure of filaments from centimeter and millimeter observations     

M. Butz  E. Fürst  W. Hirth  M. R. Kundu 《Solar physics》1975,45(1):125-129

From filament observations at centimeter and millimeter wavelengths it is shown that the transition layer between the dense, cool filamentary material and the ambient hot, rarified corona is rather thin, of the order of some hundred kilometers. Hence, the difference in the sizes of filaments in the radio and optical domains is of the order of 1000 km or 2, thus not detectable by the instruments so far used for observations of filaments.NASINRC Resident Research Associate at NASA-GSFC.  相似文献   

The potassium abundance in the solar photosphere     

Ramiro De La Reza  Edith A. Müller 《Solar physics》1975,43(1):15-32

High precision center-limb spectrograms of the K i resonance doublet line at λ 7699 Å were used to study the line formation and to determine the abundance of potassium in the solar atmosphere. The LTE assumption is not valid for these lines. Synthetic profiles computed in NLTE reproduce very well the observed center-limb line behaviour and yield log? _K = 5.14±0.10 for the solar abundance of potassium (on the scale of log? _H = 12 for Hydrogen).  相似文献   

On the nature of some active regions in the microwave range     

M. Felli  G. Tofani  E. Fürst  W. Hirth 《Solar physics》1975,42(2):377-390

The radio emission of a selected number of solar active regions has been investigated with high angular resolution at two frequencies: 10 and 17 GHz. By comparing the results of the two observations the following conclusions can be drawn:

1. The brightness temperature distribution of an active region is often composed of very bright cores of small dimension (angular extent θ?20″) imbedded in extended halos of lower brightness.
2. The radio emission of such structures as well as the degree of polarization can be explained with a thermal process. The halos can originate by pure thermal bremsstrahlung while in the case of the very bright cores found at 10 GHz (brightness temperature T _b?1–9 × 10⁶K) the emission at the harmonics of the gyrofrequency is needed.

  相似文献   

Hydrology and hydrogeology of Sakaryabaşı Karstic springs, Çifteler, Turkey     

G. Günay 《Environmental Geology》2006,51(2):229-240

The Sakarya River is one of the largest rivers in Turkey and is fed mainly from Sakaryabaşı springs. The Sakaryabaşı springs are located in the Central Anatolia and issue from confined/semi-confined karst having a thermal component and therefore, having quite different hydrogeological characteristics as compared to the Taurus Karst region, a typical example of the Mediterranean type of karst. The karstic carbonate rocks that form the groundwater reservoir are overlain by a thick semi-pervious overburden of mainly clastics of Neogene age. Tectonics is the major factor controlling the occurrence of the karst springs in the area where topography is rather flat. This study aimed at explaining the occurrence and movement of the karst groundwater within the system by use of hydrogeological, chemical, and isotopic tools. Isotopic composition of the waters revealed that all waters in the region are of meteoric origin and the thermal component is due to deep circulation. The catchment area of the hydrogeological system extends to the south and groundwater movement is towards the outlets, which are in a depression along a major fault. The movement of the groundwater, based on analysis of remotely sensed images, is controlled mainly by structural elements.  相似文献   

Water temperature behaviour in the River Loire since 1976 and 1881     

Florentina Moatar  Joël Gailhard 《Comptes Rendus Geoscience》2006,338(5):319-328

Analysis of monthly mean river temperatures, recorded on an hourly basis in the middle reaches of the Loire since 1976, allows reconstruction by multiple linear regression of the annual, spring and summer water temperatures from equivalent information on air temperatures and river discharge. Since 1881, the average annual and summer temperatures of the Loire have risen by approximately 0.8?°C, this increase accelerating since the late 1980s due to the rise in air temperature and also to lower discharge rates. In addition, the thermal regime in the Orleans to Blois reach is considerably affected by the inflow of groundwater from the Calcaires de Beauce aquifer, as shown by the summer energy balance. To cite this article: F. Moatar, J. Gailhard, C. R. Geoscience 338 (2006).  相似文献   

Preparation of a geotechnical microzonation model using Geographical Information Systems based on Multicriteria Decision Analysis   总被引：3，自引：0，他引：3  

a&#x;l Kolat  Vedat Doyuran  Can Ayday  M. Lütfi Süzen 《Engineering Geology》2006,87(3-4):241-255

The purpose of this study is to develop a geotechnical microzonation model using Geographical Information Systems (GIS) based on Multicriteria Decision Analysis (MCDA). As study area, the Eskişehir downtown area has been chosen. Eskişehir is one of the most rapidly growing cities in central Turkey. The model inputs include slope, flood susceptibility, soil, depth to groundwater table, swelling potential, and liquefaction potential. The weight and rank values are assigned to the layers and to the classes of each layer respectively. The assignment of the weight/rank values and the analysis are realized by the application of two different decision models, namely Simple Additive Weighting (SAW) and Analytic Hierarchy Process (AHP) methods. The geotechnical microzonation maps prepared as outputs of these methods are found to be consistent with each other and confirmed by the experts within the study area. The geotechnical microzonation map prepared using the AHP method is recommended as the final map of the study.  相似文献