Search results for "VSR"
showing 10 items of 26 documents
Analysis of HVSR Data Using a Modified Centroid-Based Algorithm for Near-Surface Geological Reconstruction
2022
Recently, the use of microtremor techniques for subsoil investigation has increased significantly. The HVSR (Horizontal to Vertical Spectral Ratio) technique allows, in many cases, to obtain a seismo-stratigraphic reconstruction of the subsoil and to identify areas with similar seismic behavior. However, the stratigraphic interpretation of the HVSR peaks still remains a subjective choice and linked to a priori information. A non-hierarchical centroid-based algorithm was modified to group HVSR peaks of different measurements that can be attributed to the same generating seismic discontinuity. Some tests performed have shown that the proposed algorithm produces valid results even in the absen…
RNA2-encoded VP37 protein of Broad bean wilt virus 1 is a determinant of pathogenicity, host susceptibility, and a suppressor of post-transcriptional…
2020
Abstract Broad bean wilt virus 1 (BBWV‐1, genus Fabavirus, family Secoviridae) is a bipartite, single‐stranded positive‐sense RNA virus infecting many horticultural and ornamental crops worldwide. RNA1 encodes proteins involved in viral replication whereas RNA2 encodes two coat proteins (the large and small coat proteins) and two putative movement proteins (MPs) of different sizes with overlapping C‐terminal regions. In this work, we determined the role played by the small putative BBWV‐1 MP (VP37) on virus pathogenicity, host specificity, and suppression of post‐transcriptional gene silencing (PTGS). We engineered a BBWV‐1 35S‐driven full‐length cDNA infectious clone corresponding to BBWV‐…
Joint interpretation of electrical and seismic data aimed at modelling the foundation soils of the Maredolce monumental complex in Palermo (Italy)
2020
The monumental complex of Maredolce (Palermo) includes an Arab-Norman castle that stands on the banks of an artificial lake carved out of the calcarenitic rock that rests on impermeable clays. The lake was originally filled with water, thanks to the channelling of a spring. Over time, the lowering of the water table and the high hydraulic permeability of the calcarenites have caused the lake to dry up. A project to renovate the monumental complex has recently been launched. It also provides the study of a possible restoration of the original conditions of the lake. To this end, a multidisciplinary geophysical study was carried out to investigate the geotechnical conditions of permeability o…
Contribution of HVSR measures for seismic microzonation studies
2018
The HVSR method applied to seismic noise can be a very useful technique to map the site effects of the territory, to identify the thickness of the soft covering and so the depth of the seismic bedrock. The case of the urban area of Oliveri is presented. Because of its high seismic hazard this area has been subject of first level seismic microzonation. The town lies on a large coastal plain made of mixed fluvial/marine sediments, overlapping a deformed substrate. In order to identify points on the area probably suffering of relevant site effects and to define a preliminary Vs subsurface model, 23 HVSR measurements were performed. A clustering technique of continuous signals has been used to …
Contribution of the cluster analysis of HVSR data for near surface geological reconstruction
2015
The use of HVSR technique allows in many cases (Bonnefoy-Claudet et al. 2006) to obtain detailed reconstruction of the roof of the seismic bedrock (Di Stefano et al. 2014) and to identify areas with similar seismic behaviour. Theoretical considerations (Nakamura 1989) and experimental tests showed that amplification of horizontal motions between bottom and top of a sedimentary cover is well related to the ratio between the spectra of the horizontal and vertical components of the ground velocity (Nakamura 2000). This ratio is a measure of ellipticity of Rayleigh wave polarization, overlooking Love and body waves contribution. Assuming that subsoil can be represented as a stack of homogeneous…
Assessment of a geological model by surface wave analyses
2016
A set of horizontal to vertical spectral ratio (HVSR) and multichannel analysis of surface waves (MASW) measurements, carried out in the Altavilla Milicia (Sicily) area, is analyzed to test a geological model of the area. Statistical techniques have been used in different stages of the data analysis, to optimize the reliability of the information extracted from geophysical measurements. In particular, cluster analysis algorithms have been implemented to select the time windows of the microseismic signal to be used for calculating the spectral ratio H/V and to identify sets of spectral ratio peaks likely caused by the same underground structures. Using results of reflection seismic lines, ty…
A multidisciplinary non-invasive approach in geoarchaeology conducted on the archaeological area of Selinunte
2019
Southwestern Sicily is an area of infrequent seismic activity. Only an earthquake occurred in the Belice valley on 13 January 1968 is reported in the historic earthquake catalogues (see e.g. [1]) as severe event, that is characterized by moderate-high energy (M=6.5) and significant epicentral and local macroseismic intensities (Io=X and I=VII-VIII of the MCS scale). Nevertheless, some studies (e.g. [2]) suggest that probably at least two earthquakes struck this area, between the fourth century B.C. and the early Middle Ages, with energy able to damage and produce collapse in some temples of Selinunte. In this framework, we propose the use of non-invasive approaches in geoarchaeology for det…
Near surface seismostratigraphic modelling of the Bandita plain in Palermo town (Italy) from integra-ted analysis of HVSR and stratigraphic data
2016
The Horizontal to Vertical Spectral Ratio (HVSR) noise method (Nakamura, 1989) is nowadays widely used to estimate the resonance frequencies of geological structures (Bonnefoy-Claudet, 2006). However, often HVSR is also used to obtain information on the depth of the seismic bedrock and on thickness and seismic velocity of the process overburden deposits, using inversion techniques of the H/V curve (Fäh et al., 2003). This nevertheless produce results with large uncertainty intervals of parameters, and then must be necessarily constrained by detailed stratigraphic information. An application of HVSR inversion is presented in order to verify the effectiveness of this technique for purposes of…
Seismic microzonation by means of cluster analysis
2019
The identification of areas with uniform behaviour in seismic perspective is a very complex task that involves the simultaneous assessment of many parameters. In this paper we propose an automatic procedure for the seismic microzonation based on cluster analysis and performed by means of an agglomerative hierarchical algorithm. It exploits a proximity matrix specifically defined on the parameters space and the average linkage criteria. The procedure has been used to carry out the expedite seismic microzonation of some high seismic hazard areas, only using the data inferred by the extensive application of the HVSR technique. The results of the clustering procedures have been assessed from a …