Earthquake scenarios and seismic input for cultural heritage: applications to the cities of Rome and Florence

For historical buildings and monuments, i.e. when considering time intervals of about a million year (we do not want to loose cultural heritage), the applicability of standard estimates of seismic hazard is really questionable. A viable alternative is represented by the use of the scenario earthquakes, characterized at least in terms of magnitude, distance and faulting style, and by the treatment of complex source processes. Scenario-based seismic hazard maps are purely based on geophysical and seismotectonic features of a region and take into account the occurrence frequency of earthquakes only for their classification into exceptional (catastrophic), rare (disastrous), sporadic (very strong), occasional (strong) and frequent. Therefore they may provide an upper bound for the ground motion levels to be expected for most regions of the world, more appropriate than probabilities of exceedance in view of the long time scales required for the protection of historical buildings. The neo-deterministic approach naturally supplies realistic time series of ground motion, which represent also reliable estimates of ground displacement readily applicable to seismic isolation techniques, useful to preserve historical monuments and relevant man made structures. This methodology has been successfully applied to many urban areas worldwide for the purpose of seismic microzoning, to strategic buildings, lifelines and cultural heritage sites; we will discuss its application to the cities of Rome and Florence

Simulation of the 2009, Mw = 4 Tehran earthquake using a hybrid method of modal summation and finite difference

The Greater Tehran Area is the most important city of Iran and hosts about 20% of the country?s population. Despite the presence of major faults and the occurrence of historical earthquakes, the seismicity is relatively low at present. Thus, it is important to estimate the ground motion for preventive, reliable seismic hazard assessment. An earthquake with magnitude Mw = 4, which occurred close to Tehran, 17 October 2009, is the first local earthquake that has been recorded by the local strong ground motion network in Tehran. To simulate the ground motion caused by the earthquake a hybrid technique is used. It combines two methods: the analytical modal summation and the numerical finite difference, taking advantage of the merits of both. The modal summation is applied to simulate wave propagation from the source to the sedimentary basin and finite difference to propagate the incoming wavefield in the laterally heterogeneous part of the structural model that contains the sedimentary basin. Synthetic signals are simulated along two East?West and Southeast?Northwest profiles. Frequency, response spectra, and time domain, waveforms and peak values, parameters are computed synthetically and compared with observed records. Results show agreement between observed and simulated signals. The simulation shows local site amplification as high as 6 in the southern part of Tehran

Characterization of the Elastic Displacement Demand: Case Study - Sofia City

The results of the study on the seismic site response of a part of the metropolitan Sofia are discussed. The neo-deterministic seismic hazard assessment procedure has been used to compute realistic synthetic waveforms considering four earthquake scenarios, with magnitudes M=3.7, M=6.3 and M = 7.0. Source and site specific ground motion time histories are computed along three selected cross sections, making use of the hybrid approach, combining the modal summation technique and the finite differences scheme. Displacement and acceleration response spectra are considered. These results are validated against the design elastic displacement response spectra and displacement demand, recommended in Eurocode 8. The elastic response design spectrum from the standard pseudo-acceleration, versus natural period, Tn, format is converted to the Sa Sd format. The elastic displacement response spectra and displacement demand are discussed with respect to the earthquake magnitude, the seismic source-to-site distance, seismic source mechanism and the local geological site conditions

Cani lenti

Quella fra Franco Vaccari e gli animali è un'alleanza che emerge carsicamente in moltissime delle sue opere: Luca Panaro conduce un dialogo con l'artista per rivelarne origini, evoluzioni e significati

Preliminary Neo-Deterministic Seismic Hazard Assessment in Pakistan and Adjoining Regions

The regional seismic hazard in Pakistan and adjoining regions is assessed using the Neo-deterministic seismic hazard assessment approach (NDSHA). Synthetic seismograms are generated by the modal summation technique at the nodes of a grid that covers the studied area. The main input for the computations consists of a set of earthquake sources and of the structural model where the seismic waves propagate. The earthquake sources are parameterised within the active seismogenic areas by defining the focal mechanism, the depth and the magnitude, obtained through the analysis and re- elaboration of the past seismicity. The peak displacement (Dmax), peak velocity (Vmax) and design ground acceleration (DGA) are then extracted from the synthetic signals and plotted on the 0.2\ub0 x 0.2\ub0 grid to construct the seismic hazard map of the studied area. There are few probabilistic hazard maps available for Pakistan, however, this is the first study aimed at producing a neo-deterministic seismic hazard map for Pakistan and adjoining regions.The most severe hazard is found in the epicentral zone of the great Muzaffarabad earthquakes of 2005 and its surroundings, where the DGA estimate falls in the highest range 0.60 g \u2013 1.2 g. The peak velocity and displacement in the same region are estimated as 60 12120 cm s 121 and 30 1260 cm, respectively

Carbon Dioxide Emissions of the City Center of Firenze, Italy: Measurement, Evaluation, and Source Partitioning

AbstractAn eddy covariance station was installed in the city center of Firenze, Italy, to measure carbon fluxes at half-hourly intervals over a mostly homogeneous urban area. Carbon dioxide (CO2) emission observations made over an initial period of 3.5 months were compared with indirect estimates of CO2 emissions based on inventory data sources of vehicle circulation and natural gas consumption for domestic heating and cooking. Such a comparison provided proper evaluation of the measurements. Using seasonal dynamics of observed fluxes, the overall CO2 source of the city center was partitioned into its major components (i.e., road traffic and domestic heating). Results were directly compared with CO2 source estimates based on inventory sources

A seismological and engineering perspective on the 2016 Central Italy earthquakes

The strong earthquake (M 6.0-6.2) that hit the central Apennines on August 24, 2016, occurred in one of the most seismically active areas in Italy. Field surveys indicated severe damage in the epicentral area where, in addition to the loss of human life, widespread destruction of cultural heritage and of critical buildings occurred. Using the neo-deterministic seismic hazard assessment (NDSHA), we apply the maximum deterministic seismic input (MDSI) procedure at two of the most relevant sites in the epicentral area, comparing the results with the current Italian building code. After performing an expeditious engineering analysis, we interpret as a possible cause of the reported damages the high seismic vulnerability of the built environment, combined with the source and site effects characterising the seismic input. Therefore, it is important to design and retrofit with appropriate spectral acceleration levels compatible with the possible future scenarios, like the ones provided by MDSI

Trilobita

Los trilobites fueron artrópodos marinos paleozoicos, provistos de una cutícula dorsal mineralizada (exoesqueleto) y fosilizable, la que permitió que tengan gran representación en el registro fósil. Desde que aparecen en el Cámbrico Temprano, su diversidad alcanzó valores elevados en el Cámbrico Tardío-Ordovícico, para decrecer durante el Silúrico-Devónico y reducirse aún más en el Paleozoico Tardío, antes de extinguirse a fines del Pérmico. Durante los 300 m.a. de su historia evolutiva, estos organismos desarrollaron una amplia gama de modificaciones en el exoesqueleto, adquiriendo distintos hábitos de vida y notable capacidad de adaptación a los diversos ambientes marinos, desde sublitorales hasta profundos. Aunque la mayoría posee tamaños que oscilan entre 30 y 100 mm, muchos alcanzan dimensiones desde 2 mm hasta más de 70 cm. Se describieron alrededor de 5000 géneros y gran cantidad de especies, muchas de ellas valiosas en la resolución de problemas estratigráficos, paleobiogeográficos y paleoecológicos.Facultad de Ciencias Naturales y Muse

Fate of soil organic carbon and polycyclic aromatic hydrocarbons in a vineyard soil treated with biochar

The effect of biochar addition on the levels of black carbon (BC) and polcyclic aromatic hydrocarbons (PAHs) in a vineyard soil in central Italy was investigated within a two year period. Hydropyrolysis (HyPy) was used to determine the contents of BC (BCHyPy) in the amended and control soils while the hydrocarbon composition of the semi-labile (non-BCHyPy) fraction released by HyPy was determined by gas chromatography-mass spectrometry, together with the solvent-extractable PAHs. The concentrations of these three polycyclic aromatic carbon reservoirs, changed and impacted differently on the soil organic carbon over the period of the trial. The addition of biochar (33 ton dry biochar ha-1) gave rise to a sharp increase in soil organic carbon which could be accounted for by an increase of BCHyPy. Over time, the concentration of BCHyPy decreased significantly from 36 to 23 mg g-1, and as a carbon percentage from 79% to 61%. No clear time trends were observed for the non-BCHyPy PAHs varying from 39 to 34 µg g-1 in treated soils, not significantly different from control soils. However, the concentrations of extractable PAHs increased markedly in the amended soils, and decreased with time from 153 to 78 ng g-1 remaining always higher than those in untreated soil. The extent of the BCHyPy loss was more compatible with physical rather than chemical processes