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Shear-wave Velocity Database as key Input for Seismic Site Amplification Models in Bucharest City, Romania
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 11th Congress of the Balkan Geophysical Society, Oct 2021, Volume 2021, p.1 - 5
Abstract
The contribution of local site effects to seismic hazard is significant in cities located on thick stack of loose Quaternary layers of sediments such as Bucharest City. Here, strong-motion recordings of major intermediatedepth Vrancea earthquakes in 1986 and 1990, as well as the disastrous effects of previous major earthquakes (in 1940 or 1977) proved the necessity and importance of microzonation maps not only for new building design, but also for a great part of Bucharest old buildings stock, which is in a critical need for urgent retrofitting. Some studies emphasized the conclusion that mean shear-wave velocities (Vs) corresponding to the main 7 geological layers in the Bucharest underground: i) are important and must be known until deeper depth of 100- 150 m, making Vs-30 an insufficient and obsolete proxy for the explanation of spectral acceleration peaks at surface (Bala et al., 2014); ii) in surface the values of Vs may vary considerably across the city in just a few hundreds of meters.