1.        Narayan, J. P. and A. Ram (1994): Application of acustic wave solution for the analysis of reverberation. Geofizika, 11, 1-13.  

 

ABSTRACT:

 

       Finite difference method offers a versatile approach to numerical computation of synthetic seismograms for give subsurface complex geological model. Numerical solution for the acoustic wave has been derived using the Lax-Wendroff scheme for an inhomogeneous medium and implemented for the modeling of localized area in the offshore region. Numerical seismograms have been obtained to identify the singing effect for different model geometries. The effect of source-receivers position, water depth and the frequency of source on the reverberation is studied. The generation of ghost reflections and its effect on the amplitude of reflected waves as well as on multiples for different source-depth position is studied. The grid dispersion effect on the reflected signal and the reverberation is discussed for high-frequency signals. The analysis of numerical seismograms indicates that the energy radiating from a point source and remaining completely within a water layer may not cause singing, whereas the energy reflected from the deeper horizons is responsible for the singing effect on the reflections.

 

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2.        Mahajan, A. K. and S. Kumar (1994): Linear features registered on the Landsat imagery and seismic activity in the Dharamsala-Palampur region (NW Himalaya). Geofizika, 11, 15-25.

 

ABSTRACT:

 

       The Dharamsala-Palampur region of Kangra district (Himachal Pradsh, NW Himalaya) has been studied to infer the stress filed pattern and tectonic movements responsible for the generation of high seismicity in the region. The referred area reveals large number of lineaments, generally a manifestation of various structural features like folds, faults, fractures, etc. The different types of lineaments were differentiated through a lineament filter map. The rose diagram and linear histogram of lineaments are drawn to reveal major trend of linears and their correlation with the seismicity of the region. The major thrust systems are cut and offset by the transverse lineaments which have direct relationship with the complex tectonic history of this region. 

 

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3.        Jurčec, V. and S. Visković (1994): Mesoscale characteristics of southern Adriatic bora storms. Geofizika, 11, 33-46.   

 

ABSTRACT:

 

       The bora in Dalmatia is compared to the better known bora in the northern Adriatic. Fifteen severe storms in Split are selected during the period January 1980 to January 1983.

       It is shown that in most cases such a severe bora does not last long, but the gusts are above 30 m s^-1, with the absolute maximum of 45 m s^-1, and therefore it is comparable with the strength of northern Adriatic bora. The mean surface pressure distribution and AT 500 hPa for these cases emphasize a mesoscale cyclone in the southern Adriatic, which may or may not be seen on large scale (synoptic) charts. Two “bora types” according to local weather characteristics are distinguished. “Dark bora” (cyclonic type) with cloudy sky and precipitation is characterized by deeper surface cyclone and a pronounced upper-level trough from Baltic to the southern Adriatic, in contrast to cloudiness (anticyclonic) “clear bora” when mesoscale cyclone is further to the east of Adriatic. The upper level flow in latter case shows a cut-off low with N-NE current above the bora throughout the troposphere. These patterns are in agreement with Defant’s (1951) description of cyclone and anticyclone bora types; they stress both upstream and downstream influence and emphasize the interaction of large-, meso- and local-scale processes on the Dalmatian bora flow.

       The ALPEX bora case of 11-15 March 1982 illustrates local differences in bora occurrence and strength along the Adriatic, and the time cross sections exhibit the characteristics of upstream vertical atmospheric structure for bora onset and decay.

 

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4.        Grabovec, D. and I. Allegretti (1994): On the digitizing of historical seismograms. Geofizika, 11, 27-31. 

 

ABSTRACT:

 

       The pens of early mechanical seismographs record a curved rather than the straight line when the pendulum is shifted from the equilibrium position. Consequently, the abscissa of the seismogram is generally not a linear function of time. This can be avoided by simple corrections. The first one changes the digitized coordinates into those of the zero line of the seismogram, and the second one transforms the zero line coordinates to the nonlinear time scale. This process will preserve both amplitudes of displacement and the time history of the seismogram.

 

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5.        Vilibić, I. (1994): Modified Gaussian plume model and K-tranport and diffusion model efficiency in the same atmospheric conditions. Geofizika, 11, 47-57. 

 

ABSTRACT:

 

       The aim of this paper is to compare the modified Gaussian plume model and K-model for continuous emission sources in weakly orographically developed regions. Parameterization of input variables is based on the physical methods using similarity theory.

       The results show that, when strong winds and stable atmosphere are present, ground level concentrations take similar values. In contrary, when weak winds and unstable atmosphere are present, K-model overestimates values given by Gaussian model due to exclusion of plume rise in the process of diffusion parameterization.

 

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