Microzonation of Bucharest: State-of-the-Art

Abstract

The 1940 (Mw 1⁄4 7.7) and 1977 (Mw 1⁄4 7.4) Vrancea earthquakes (Romania) inflicted heavy damage and casualties in Bucharest and the statistics indicate a recurrence interval of 25 years for Mw ‡ 7.0 events. Under these circumstances, the seismic microzonation represents important information for detailed urban planning that establishes an appropriate level of preparedness to the earthquake threat. This paper reviews the main studies concerning the seismicity of the Vrancea region, the site conditions of the city, the characterization of the building stock, and the codes of practice that regulate the antiseismic design. The first-order microzonation of Bucharest was performed starting from the existing database of structural and geotechnical parameters. New insights originating from direct instrumental observation and interpretation of the local effects as well as realistic numerical modeling that update and improve the input data necessary for a detailed microzoning map of the city are also discussed

Ground-motion prediction equations for the intermediate depth Vrancea (Romania) earthquakes

“…1b). The cohesionless layered Quartenary deposits with a total thickness of more than 600 m are largely developed in the area (e.g., Mandrescu 1972;Moldoveanu et al 2004). The lithological formations are characterized by strong lateral variations in depth and thickness.…”

Broadband frequency-dependent amplification of seismic waves across Bucharest, Romania

“…As resonant frequencies of residential buildings a few stories high are typically above 1 Hz and short-period seismological sensors are mostly used, this part of the seismic wavefield is usually analysed for hazard assessment. However, in Bucharest, the capital of Romania, the fundamental frequency range of many vulnerable buildings is 0.5-1.5 Hz (Lungu et al 1994); such low frequencies are also observed during earthquake shaking (Aldea et al 2004;Moldoveanu et al 2004). These buildings are multi-storied (from nine to eleven floors), and they have already been partly damaged by World War II actions and major earthquakes in 1940, 1977and 1986).…”

Multidisciplinary co-operation in building design according to urbanistic zoning and seismic microzonation

“…In 1977 another strong Vrancea-earthquake (M w =7.4), leaded to greatest destruction in Bucharest. Moldoveanu et al (2004) reviewed seismic microzonations of Bucharest performed after 1940. Seismic microzoning maps were drawn prior to 1977 after Russian model, considering the influence of the surface soil layer and water table level on the building behaviour.…”

“…The microzonation increasingly contributes to seismic risk evaluation in urban areas. Urban microzonation is researched by the groups of Parvez et al (2004), Moldoveanu et al (2004), Panza et al (2001), Ansal (2002), and Faccioli and Pessina (2003). Parvez et al (2004) initiated a project towards an integrated expert system, to use seismic microzonation parameters together with information on the earth, environmental, socioeconomic and political systems, in urban planning processes, when elaborating land-use maps, able to provide well estimated seismic inputs for earthquake resilient building design.…”

“…Moldoveanu et al (2004) described the Bucharester topography as a plane sloped in the SE direction of two river flows, dividing it into morphological units:…”