Comparison between VS30 and other estimates of site amplification in Italy

During 5 microzonation projects in Italy, we had access to 46 estimates of Vs30 (30 obtained with down-hole or cross-hole measurements, plus 10 velocity profiles obtained with surface techniques, 6 sites were considered A without drilling, being rock sites). In all the sites we performed HVNR measurements to verify the presence of a resonant frequency and in 34 sites we installed seismic instrumentation to record earthquakes and estimate site amplification using HVSR. It is important to note that we did not pre-selected the sites, but just followed the requests of two Regional governments (Marche and Basilicata) to study a set of localities that were chosen for reasons other than geo-morphological ones (previous earthquakes, pilot studies, design of new infrastructures). The comparison between site seismic amplification and Vs30 showed that this last parameter is not a good proxy of observed site effects. The reason why in Italy Vs30 does not provide satisfactory estimates is linked to peculiar geological settings that are widespread in our country. The main problems encountered are underestimations by Vs30 at sites with velocity inversions and overestimations on deep basins. Vs30 seems to work fine only if a site has a strictly monotonic velocity profile increasing with depth and a strong impedance contrast in the first dozen meters. Further data will be available thanks to an ongoing national project funded by the Civil Defence Department that is focusing on Vs30 estimates in the presence of velocity inversions, fractured rock masses, landslides and karst areas

Non-parametric analysis of a single seismometric recording to obtain building dynamic parameters

We propose a simple time-domain, non-parametric method to estimate the damping at the fundamental frequency of a building. The method aims at obtaining quick-and-dirty data on large sets of buildings, at the expenses of the accuracy provided by other, more complex and resource-demanding techniques. The analysis of a 10 min recording of ambient vibration with a single high-resolution seismometer atop the building can provide a good estimate of the required parameters for the first flexural modes on orthogonal components. The proposed methodology does not require complex filtering and assumptions on signal structure, nor multiple measurement points or clear single transients induced by shakers, shocks or release tests. We checked the stability of the proposed method in terms of duration and characteristics of the signal, and compared the results obtained by others with standard techniques. Then, we tested the ability of the proposed technique to identify damping and frequency variations due to large displacements, damage or changes in the structural characteristics. The proposed methodology provides a satisfactory agreement when compared with other techniques. Even if it is not always possible to obtain higher modes, the advantage is that it is possible to study with limited resources the fundamental parameters for a large number of buildings. This is useful to include experimental data on building behaviour in microzonation studies

An attenuation study in Southern Italy using local and regional earthquakes recorded by seismic network of Basilicata

We determined a set of empirical functions that describe the spectral amplitude decay of S-waves with distance in Southern Italy. We analyzed 32 earthquakes with magnitudes ML 2.0-5.4 and hypocentral distances ranging between 12 and 216 km. We obtained attenuation functions for 14 frequencies(1.0< f<20.0 Hz). We compared these functions with average non-parametric attenuation functions reported by Castro et al. (1999) for different regions of Italy, and we observe that at low frequencies (f<5.0 Hz) the spectral amplitudes from earthquakes in Southern Italy decay faster than the average. However, at high frequencies ( f > 5.0 Hz), the spectral amplitudes are above the average. At higher frequencies ( f > 10 Hz), the attenuation functions obtained for Southern Italy are slightly above the standard deviation of the average attenuation functions. It is possible that in this frequency range (10-20 Hz) site effects may influence the amplitude decay. In order to quantify the attenuation of the S-waves, we estimated the quality factor Q modeling the empirical attenuation functions using the following parametric form: A( f , r)=10/r b·e- pfR/Q ß; where 1.6 = f = 10.0 Hz is the frequency band with minimum effect of instrument and site response, r = 120 km is the distance range where the rate of decay of the spectral amplitudes is approximately constant, R=(r-10) and ß=3.2 km/s. We found that the exponent b=1.0±0.2 in the frequency band analyzed and Q shows a frequency dependence that can be approximated by the function Q=32.1 f 1.7

Reappraisal of a XVI century earthquake combining historical, geological and instrumental information

The earthquake occurred during 1561 in Southern Italy heavily struck a zone known as Vallo di Diano. This is the only destructive earthquake whose epicentre is attributed to that valley. Two problems arise about this epicentral location: 1)the distribution of reported effect is highly asymmetrical, possibly reflecting population distribution at that time, 2)some geologist maintain that there is no evidence for ongoing active tectonics in the Vallo di Diano area. The basic question behind our work is the following: Is it possible that both expert judgement and computer techniques have up to now placed the 1561 epicentre in the wrong place, driven by asymmetrical distribution of observations and by site effects enhancing damage in the alluvial valley? It was possible to demonstrate that, when site amplification are taken into account, the location of an historical earthquake can vary significantly. This applies not only to epicentre but especially to extended seismogenic faults connected to large events. From the seismogenic point of view, we demonstrate that the location of the 1561 in the Melandro valley is more statistically significant than the one up to know proposed. More detailed geological data are however needed to lend support to the Val Melandro fault hypothesis

Buildings as a seismic source: analysis of a release test at Bagnoli, Italy

Taking advantage of a large displacement-release experiment on a twostory reinforced concrete building located in Bagnoli (Naples, Italy), we performed free-field measurements using 3D seismometers, accelerometers, and a 100-m-long vertical array. The ground motion was noticeable: near the building, the acceleration exceeded 5% g. At each measurement point, it was possible to recognize two source terms, due to the tested building and to the reaction structure. The two sources generated different wave trains. High-frequency accelerations propagated as Rayleigh waves, whereas 1–2 Hz waves carrying most of the displacement propagated only as body waves. The experiment lends further support to the hypothesis that buildings are able to modify substantially the free-field ground motion in their proximity: the peak ground acceleration we observed is the 20% of the ground acceleration required to produce a displacement on the building equal to the one imposed during the release test. We recognize, however, the difficulty of a realistic modeling of wave propagation in the topmost layer of a densely urbanized area

Numerical modelling and in-situ experiment for self-sealing of the induced fracture network of drift into the Callovo-Oxfordian claystone during a hydration process

The excavation damage zone surrounding an underground tunnel/gallery, and in particular its evolution, is being studied for the performance assessment of a radioactive waste underground repository. This paper focuses on numerical analysis of the self-sealing of the damaged zone based on an in-situ CDZ experiment for exploring the self-sealing of excavation damage zone during a hydration process. A plastic damage model is employed to describe the mechanical behaviour of Callovo-Oxfordian claystone (COx), and an added deformation model coupled with the standard Biot's model to simulate the significant deformation of COx claystone during the change of water content. Crack estimation and permeability evaluation of unsaturated fractured COx claystone are carried out through a post-processing method based on the fracture energy regularization and the cubic law, respectively. The validation of the proposed model is performed by numerical simulation of: (1) COx claystone swelling and triaxial compression tests, (2) self-sealing of fractured COx claystone samples during hydration process, (3) self-sealing of the damaged zone during a hydration process. Comparisons between the numerical and experimental results demonstrate the reliability of the proposed model to accurately describe the self-sealing of the fractured COx claystone, and the global water permeability reduction in hydration illustrates the accomplishment of the self-sealing of damaged zone

Towards specific T–H relationships: FRIBAS database for better characterization of RC and URM buildings

FRIBAS database is an open access database composed of the characteristics of 312 buildings (71 masonry, 237 reinforced concrete and 4 mixed types). It collects and harmonizes data from different surveys performed on buildings in the Basilicata and Friuli Venezia Giulia regions (Southern and Northeastern Italy, respectively). Each building is defined by 37 parameters related to the building and foundation soil characteristics. The building and soil fundamental periods were experimentally estimated based on ambient noise measurements. FRIBAS gave us the opportunity to study the influence of the main characteristics of buildings and the soil-building interaction effect to their structural response. In this study, we have used the FRIBAS dataset to investigate how the building period varies as a function of construction materials and soil types. Our results motivate the need of going beyond a 'one-fits-all' numerical period-height (T-H) relationship for generic building typologies provided by seismic codes, towards specific T-H relationships that account for both soil and building typologies

Genetic Diversity of Pseudomonas syringae pv. actinidiae Strains from Different Geographic Regions in China

Pseudomonas syringae pv. actinidiae causes kiwifruit bacterial canker, with severe infection of the kiwifruit plant resulting in heavy economic losses. Little is known regarding the biodiversity and genetic variation of populations of P. syringae pv. actinidiae in China. A collection of 269 strains of P. syringae pv. actinidiae was identified from 300 isolates obtained from eight sampling sites in five provinces in China. The profiles of 50 strains of P. syringae pv. actinidiae and one strain of P. syringae pv. actinidifoliorum were characterized by Rep-, insertion sequences 50, and randomly amplified polymorphic DNA polymerase chain reaction (PCR). Discriminant analysis of principal coordinates, principal component analysis, and hierarchical cluster analysis were used to analyze the combined fingerprints of the different PCR assays. The results revealed that all isolates belonged to the Psa3 group, that strains of P. syringae pv. actinidiae from China have broad genetic variability that was related to source geographic region, and that Chinese strains can be readily differentiated from strains from France but are very similar to those from Italy. Multilocus sequence typing of 24 representative isolates using the concatenated sequences of five housekeeping genes (cts, gapA, gyrB, pfk, and rpoD) demonstrated that strain Jzhy2 from China formed an independent clade compared with the other biovars, which possessed the hopH1 effector gene but lacked the hopA1 effector gene. A constellation analysis based on the presence or absence of the four loci coding for phytotoxins and a cluster analysis based on the 11 effector genes showed that strains from China formed two distinct clades. All of the strains, including K3 isolated in 1997 from Jeju, Korea, lacked the cfl gene coding for coronatine. In contrast, the tox-argK gene cluster coding for phaseolotoxin was detected in K3 and in the biovar 1 strains (K3, Kw30, and Psa92), and produced a false-positive amplicon for the hopAM1-like gene in this study. To date, only one biovar (biovar 3) is represented by the strains of P. syringae pv. actinidiae from China, despite China being the center of origin for kiwifruit

Geological and geophysical characterization of the southeastern side of the High Agri Valley (southern Apennines, Italy)

Abstract. In the frame of a national project funded by Eni S.p.A. and developed by three institutes of the National Research Council (the Institute of Methodologies for Environmental Analysis, the Institute of Research for Hydrogeological Protection and the Institute for Electromagnetic Sensing of the Environment), a multidisciplinary approach based on the integration of satellite, aero-photogrammetric and in situ geophysical techniques was applied to investigate an area located in the Montemurro territory in the southeastern sector of the High Agri Valley (Basilicata Region, southern Italy). This paper reports the results obtained by the joint analysis of in situ geophysical surveys, aerial photos interpretation, morphotectonic investigation, geological field survey and borehole data. The joint analysis of different data allowed us (1) to show the shallow geological and structural setting, (2) to detect the geometry of the different lithological units and their mechanical and dynamical properties, (3) to image a previously unmapped fault beneath suspected scarps/warps and (4) to characterize the geometry of an active landslide affecting the study area

Corrigendum to "Geological and geophysical characterization of the southeastern side of the High Agri Valley (southern Apennines, Italy)" published in Nat. Hazards Earth Syst. Sci., 15, 315–323, 2015

No abstract available