Single-Station Sigma Analysis for Romanian Seismic Network

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

Romania is exposed to high seismic hazard due to Vrancea seismogenic region, where ~3 earthquakes with M>7 occurs per century at intermediate-depths (60-170 km). The impact of such strong intermediate-depth events transcends the national borders with significant damage being reported in neighboring countries (eg observed intensities of VII-VIII at more than 250 km epicentral distances during 1940 event Mw=7.7).

In this study, the efficiency of some selected GMPE’s developed for active subduction zones(Sokolov et al., 2008; Vacareanu et al., 2016; Abrahamson et al., 2015; Atkinson & Boore, 2003; Garcia et al., 2005; Lin & Lee, 2008) was tested for peak ground acceleration(PGA), spectral accelerations (SA) and peak ground velocity(PGV).

The database used comprises 3550 records of 170 Vrancea intermediate depth events with Mw=4-7.4. These data were recorded by 130 seismological stations from the Romanian National Seismic Network or collected during national/international projects, since 1977.

The comparison between the computed and recorded parameters shows that three GMPE's fit well the data within the model’s magnitude validity range(Mw>5) and over predict the values below this magnitude. In this context, the model developed from local seismicity (Vacareanu et al., 2016) was adjusted for the actual database. Different test-scenarios performed with this version indicate that the model still needs additional site correction parameters. In order to minimize the local random variability of the computed ground motion, the single sigma station was performed for each station. In case of the stations located outside of the Carpathian bend, a strong correlation is observed between the site correction term and geological conditions. Through the assessment of single station standard deviation, the aleatory uncertainties in ground motion computation were proper quantified and will lead to significant improvements in seismic hazard and risk evaluations based on expected scenarios.

Presenting Author: Elena Manea

Authors