LIVIU CONSTANTINESCU and D. ENESCU
The Centre for Geophysical Research of the Academy of the Romanian People's
Republic
Representable by the theoretical source of the dislocation theory, the foci
of the Vrancea intermediate earthquakes release an energy which, connected
to the magnitude by a relation of well-known type (Formula 1) may also be calculated
by means of an expression derived within the framework of this theory (Formula
2). Performing such calculations for the Vrancea earthquakes (Table 1) has
allowed to recognize as best fit to this case a certain formula of type 1 (Formula
4, Figure 1). In this way a firm basis is laid for establishing relations of
certain focal parameters with magnitude (Formula 5, Figure 2) and with energy
(Formula 6) as well as between earthquake energy and intensity within the epicentral
zone (Table 2, Formula 7, Figure 3).
An attempt is also made to characterize the seismic regime of the Vrancea region.
The recurrence tendency of earthquakes of a given energy class is estimated
by establishing relations of their frequency of appearance with the energy
class (Tables 3 and 5, Formulae 8 and 11, Figures 4 and 6) and with the magnitude
(Table 4, Formulae 9, 9' and 9", Figure 5). Simultaneously the "universal" parameter
of the seismic regime" is defined for the Vrancea region, in good agreement
with the average value generally adopted and with the observational data. Two
other parameters of the seismic regime are equally defined within this framework:
the seismic activity (Formulae 10, 11, 12 and 13) and the spreading of the
earthquake recurrence tendency with respect to the ideal periodicity (Table
6). Finally, numerical values are computed for the seismicity (Formula 14 and
Expression 15) and for the "tectonic flux" (Formula 16 and Expressions
17) characterizing the Vrancea Region.