Time-clustering analysis of the 1978–2008 sub-crustal seismicity of Vrancea region

The analysis of time-clustering behaviour of the sub-crustal seismicity (depth larger than 60 km) of the Vrancea region has been performed. The time span of the analyzed catalogue is from 1978 to 2008, and only the events with a magnitude of <i>M</i><sub>w</sub> ≥ 3 have been considered. The analysis, carried out on the full and aftershock-depleted catalogues, was performed using the Allan Factor (AF) that allows the identificatiion and quantification of correlated temporal structures in temporal point processes. Our results, whose significance was analysed by means of two methods of generation of surrogate series, reveal the presence of time-clustering behaviour in the temporal distribution of seismicity data of the full catalogue. The analysis performed on the aftershock-depleted catalogue indicates that the time-clustering is associated mainly to the aftershocks generated by the two largest events occurred on 30 August 1986 (<i>M</i><sub>w</sub> = 7.1) and 30 May 1990 (<i>M</i><sub>w</sub> = 6.9)

Probabilistic seismic hazard analysis of Moldova and adjacent territories

A new approach to seismic hazard assessment is proposed. It means that in a certain location of the Earth’s surface during the time t will occurs a certain number n of shakes and m of them with intensity Ik. The algorithm of seismic hazard estimation in terms of macroseismic scale and "EUROCODE 8" standard are elaborated. The cluster analysis has identified in Romania 13 seismic zones. For define the distribution of earthquakes parameters the Markov model of identified seismic zones seismicity is constructed. The PSHA of Bulgaria, Romania and Moldova territories on the basis of ROMPLUS catalogue is carried out