DOREL ZUGRAVESCU1, ILEANA FATULESCU1,
LIVIU CONSTANTINESCU2, DUMITRU ENESCU1
1Centrul de Fizica Pamantului si Seismologie,
Laboratorul de Geodinamica, Bucuresti
2Comitetul National Roman de Geodezie si Geofizica, Bucuresti
(ABSTRACT)
In continuation of previous researches concerning the correlation between
Earth tide and earthquake occurrence, further statistical analyses were carried
out in the problem, on the basis of a wider and better observational material.
It was established that significantly greater numbers of earthquakes are triggered
during the time intervals corresponding to the points of maximum, minimum and
inflexion of the gravity tide curve. Focal mechanism solutions indicate for
the earthquakes corresponding to the maximum a parallelism of the fault plane
directions with Carpathian Arc but transversality in the case of those corresponding
to the minimum, in both cases the compressional stress direction being almost
horizontal. For the earthquakes triggered within the interval of inflexion
of the curve it is suggested that they belong to the category of earthquakes
presenting a nearly vertical compressional stress direction.
The prospect of contributing to elaborating a focal mechanism hypothesis for
the Vrancea earthquakes, at least by providing criteria for discriminating
between proposed hypothesis, is contemplated. The intention of performing similar
researches for the Hindu Kush earthquakes, which present similarities with
those of Vrancea, is also expressed.
Key words: gravity tide, seismic triggering; compressional stress.