Estimation of Site Effects in Bucharest Caused by the May 30\u201331, 1990, Vrancea Seismic Events

he Vrancea region seismicity, characterized by focal depths larger than 60 km and major events with magnitudes Mw ] 6.9, is responsible for the most destructive effects experienced in the Romanian territory, and may seriously affect high risk construction located on a wide area, from Central to Eastern Europe. This seismogenic volume must be taken into account both for seismic hazard analysis at the regional level (southeastern Europe) and national level (Romania and Bulgaria) as well as for microzonation studies of the highly populated cities located in the range of influence of this source. Since about four destructive earthquakes occur every century in Vrancea, the microzonation of Bucharest, the main city exposed to the potential damages due to these strong intermediate-depth shocks, represents an essential step towards the mitigation of the local seismic risk. Two main approaches can be considered for the evaluation of the local seismic hazard: (a) collection and extended use, for engineering purposes, of the recorded strong motion data, and (b) advanced modelling techniques that allow us the computation of a realistic seismic input, which can compensate for the lack of strong motion records, actually available only for a few events that occurred in the last 20\u201330 years. Using a ground motion simulation technique that combines modal summation and finite differences, we analyze, along a geologic profile representative of the Bucharest area, the differences in the expected ground motion when two source mechanisms corresponding to the May 30\u201331, 1990, intermediate-depth Vrancea earthquakes, typical events for the Vrancea seismogenic zone, are considered. All three components of motion are influenced by the presence of the deep alluvial sediments, the strongest local effect being visible in the transversal (T) one, both observed and computed. The details of the local effects vary with varying the earthquake scenario, R and V components being very sensitive. Therefore, for a reliable determination of the seismic input all three components of motion (R, V and T) should be used

Deterministic modeling for microzonation of Bucharest: case study for August 30, 1986 and May 30-31, 1990 Vrancea earthquakes

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Evaluation of ACSM response to different mixtures of organic and inorganic solutions, and assessing the impact on organic source apportionment results

Real time and long-term monitoring of aerosol chemical species is the subject of great scientific concerns and numerous technological developments. The Aerodyne Aerosol Chemical Speciation monitor (ACSM) has been developed for this purpose. It is currently operational at over 60 monitoring stations worldwide, with almost half of them being located in Europe (notably within the Aerosols, Clouds, and Trace gases Research InfraStructure). Understanding the reponse of these instruments to different chemical species and quantifying any possible artefacts is essential if we are to use these measurements for comparative studies and for model evaluation and development. A few recent studies have illustrated such possible measurement artefacts, notably at the mz44 peak (Crenn et al, 2015, Frohlich et al, 2015). The related variability in instrument response has been linked to an artefact response to inorganic aerosol (Pieber et al.,2016), however more recent work has illustrated that this response is dependent on aerosol mixing state (Freney et al., 2019). Here, we present results of laboratory experiments where the mz44 artefact was evaluated for various inorganic and organic mixtures, and a co-located measurement campaign in ambient air..

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International audienc

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International audienc