The regression coefficient in the M-Io-log h relation were estimated on the basis of local magnitudes (M), epicentral intensities (Io) and focal depths (h) of 50 earthquakes which occurred in the wider region of Dinara mountain, Yugoslavia. The relation is
-M/3.18 + (log h)/1.72 + Io/3.63 -1 = 0.
Since the three-axes regression was utilized the resulting expression is valid for estimation of any of the variants on the basis of the observations of other two.
Complex experimental research of elastic properties and density of volcanics, effusives and their xenoliths in Armenian volcanic highland provided main characteristics of vertical changes in physical properties of volcanic rock in tectonic mobile structures. The experiments point to a decrease of thermoelastic stress values in lower layers of the Earth’s crust.
In this paper a case
of extremely high sea levels, which were recorded in the
It has been shown that the influence of atmospheric pressure on the sea can well be represented by the inverted barometer effect. In order to simulate the wind effect, one-dimension hydrodynamical numerical model has been developed. It was found that the model gives good results when land-based wind data are transformed into offshore data according to empirical relation published by S. A. Hsu in 1986. Moreover, it turned out that very good agreement between the observed and predicted levels can be obtained by using the value of 5×10-4 m s-1 for bottom friction coefficient, which equals the lower limit of values cited in the literature for the Adriatic area.
The frequent bora in Senj leaves less time for diurnal periodical winds development. Nevertheless there exist several wind system with a diurnal period. They are pronounced especially on the undisturbed days, when the particular branches of the systems are exchanging or superimposing such as: the sea and land breezes, the upslope and downslope wind, the valley and the mountain wind. All of these diurnal periodic wind systems exist in Senj as a consequence of the sea, land, mountain slope and valley influence (Fig. 1). The order of influence of the mentioned factors is exchanging during a day causing the counterclockwise change of wind directions, which is unusual on the Adriatic coast.
Several approaches were applied in the study of diurnal winds in Senj:
a) A choice of days was made, on the basis of the following criteria: insolation ≥ 12.0 hours, cloudiness in all of the terms < 2/10, the average hourly wind velocity < 5.0 m s-1, and finally the diurnal air pressure amplitude < 4.0 hPa. Only 30 days could fulfill such rigorous criteria during the 1959 – 1967 time interval in Senj. All of the selected days fall within four warm months between May and August.
On the basis of the wind hodograph (Fig. 2) and the diurnal course of the wind direction frequencies (Fig. 3) for the selected days, the following can be concluded:
- during night-time the wind from SE quadrant (called here SE wind) is prevailing; it is combination of the land breeze, the mountain wind blowing from Senjska draga valley and also of the weak bora wind,
- early in the morning the weak wind from NE quadrant (NE wind) prevails, which consist of the downslope wind and the land breeze,
- later during the morning the wind from NW quadrant (NW wind) develops, which is the combination of the sea breeze and the valley wind,
- in the middle of a day the wind from SW quadrant (SW wind) prevails as a combination of the sea breeze and upslope wind.
In the selected days the diurnal winds are developed over the broader area of Senj as well (Tab. 1 and 2).
The diurnal and annual frequency distribution of SE, NE, NW and SW
wind in all days of time interval 1966 – 1975 is satisfactory presented
by isolines on (Figs. 6-9). An obvious and unexpected decrease of the SE, NE,
NW and SW frequencies can be found in July. It is the consequence of the
diurnal periodic circulation system of a bigger scale, named here as the bay
circulation. The bay circulation develops in the bay east from
c) According to some general properties of the sea/land breeze and mountain circulation, a method has been developed for estimation of the prevailing circulation branch in the SE, NE, NW and SW wind. Daily branches of sea/land breeze and mountain circulation have the opposite properties: the sea breeze is more frequent in April than in October, and the upslope and valley wind is more frequent in October than in April. The night branches have just the opposite characteristics too: the land breeze is more frequent in October than in April, but the downslope wind and mountain wind is more frequent in April than in October.
The mentioned features of the sea/land breeze circulation are explained by the warmer land in April and warmer sea in October. The opposite features of the mountain circulation result from more often snow cover in mountains in April, and by heating of the deeper ground layers in April and their cooling in October.
5. Grisogono, B., N. Subanović and D. Koračin (1989): The cooling rates comparison between the longwave radiation and turbulence in nocturnal planetary boundary layer. Geofizika, 6, 87-99. (in Croatian).
It is shown that the process of the air-cooling is dominated by the divergence of the longwave radiative flux in cases of night-time clear-sky conditions and with weak wind conditions.
The parameterization of the longwave radiative flux divergence is derived according to the emissivity concept and the Stefan-Boltzman law, assuming that the water vapor is the only absorber of longwave radiative. The parameterization of the turbulent temperature flux divergence has been based on the O’Brien’s K-profile.
In a very short time increment, the effect of the turbulence is probably greater than the radiative effect, but very stable conditions and the absence of significant advection during the night change this hierarchy, and pure longwave radiative effect, like a slow-diffusive process, prevail in the total cooling rate according to the theory and experiments.
The model was tested on the Wangara experiment data. The model results agree well with observations, measurements and numerical simulations made by other authors.
Uniform Risk Response Spectrum Technique has been used to compute the geographical distribution of the threshold magnitude below which (1) there should be no damage in the well engineered structures and (2) future earthquake predictions should not cause much concern. It is shown that, if the long range planning of the seismic resistance of man made structures is based on the realistic estimates of seismic risk during their expected life, the moderate to large earthquakes, that may occur in the area, are not likely to cause much serious damage or disruption.
During nighttime clear-sky conditions and in the absence of significant advection the influence of divergence of net longwave radiative flux on thermodynamic processes could be dominant in the atmospheric boundary layer. The model which parameterizes such processes by height (35 grid points up to 2000 m) is accomplished based on the emissivity concept.
The test of the model is performed on the Wangara experiment data. The results are analyzed and discussed concerning a complex structure of the total cooling rate, especially in the lower part of the nocturnal boundary layer (region of smaller wind speeds).
collection of data on earthquakes with epicenters in S. R. Croatia began in the
framework of the UNDP/UNESCO project (1974) for events before 1971. The
earthquake catalogue for the years 1971 – 1985 is
currently in preparation. As a continuation of this effort a catalogue of earthquakes which occurred in 1986 and 1987 on the