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The InterPACIFIC project was aimed at assessing the reliability, resolution, and variability of geophysical methods in estimating the shear-wave velocity profile for seismic ground response analyses. Three different subsoil conditions, which can be broadly defined as soft-soil, stiff-soil, and hard-rock, were investigated. At each site, several participants performed and interpreted invasive measurements of shear wave velocity ( Vs ) and compression wave velocity ( Vp ) in the same boreholes. Additionally, participants in the project analysed a common surface-wave dataset using their preferred strategies for processing and inversion to obtain Vs profiles. The most significant difference between the invasive borehole methods and non-invasive surface wave methods is related to resolution of thin layers and abrupt contrasts, which is inherently better for invasive methods. However, similar variability is observed in the estimated invasive and non-invasive Vs profiles, underscoring the need to account for such uncertainty in site response studies. V S,30 estimates are comparable between invasive and non-invasive methods, confirming that the higher resolution provided by invasive methods is quite irrelevant for computing this parameter.

The main scope of the InterPACIFIC (Intercomparison of methods for site parameter and velocity profile characterization) project is to assess the reliability of in-hole and surface-wave methods, used for estimating shear wave velocity. Three test-sites with different subsurface conditions were chosen: a soft soil, a stiff soil and a rock outcrop. This paper reports the surface-wave methods results. Specifically 14 teams of expert users analysed the same experimental surface-wave datasets, consisting of both passive and active data. Each team adopted their own strategy to retrieve the dispersion curve and the shear-wave velocity profile at each site. Despite different approaches, the dispersion curves are quite in agreement with each other. Conversely, the shear-wave velocity profiles show a certain variability that increases in correspondence of major stratigraphic interfaces. This larger variability is mainly due to non-uniqueness of the solution and lateral variability. As expected, the observed variability in V-s,V-30 estimatesis small, as solution non-uniqueness plays a limited role. (C) 2015 Elsevier Ltd. All rights reserved.

Methods based on the seismic P-wave, seismic surface wave, and apparent resistivity are commonly used in the solution of several near-surface problems. However, the solution nonuniqueness and the intrinsic limitations of these methods can cause inconsistency in the final results. Dispersion curves of surface waves, P-wave traveltimes, and apparent-resistivity data were jointly inverted to obtain internally consistent and more reliable final model of P- and S-wave velocities and resistivity. A collection of 1D layered models was obtained by a deterministic joint-inversion algorithm based on the laterally constrained inversion scheme. The three data sets were jointly inverted imposing the same structure and Poisson’s ratio was introduced as a physical link between P- and S-wave velocities to better constrain the inversion. No physical link was imposed between the resistivity and the seismic velocities. The inversion algorithm was tested on synthetic data and then applied to a field case, where benchmark borehole data were available. The synthetic and field examples provided results in agreement with the true model and the existing geologic information, respectively.

Surface-wave tomography is usually applied at regional or planetary scale but represent an interesting approach also for near surface applications. We present a surface wave dispersion tomography that does not require the construction of phase or group velocity maps and which inverts path-specific dispersion data directly for 3-D Swave velocity variations. To compare it with classical multichannel surface-wave analysis we here present the application to a 2D seismic line.

The analysis of surface wave dispersion represents an important exploration method at different scales. The basic scheme of the method is mainly based on 1D assumption, but laterally varying sites can be resolved if an opportune processing and inversion strategy is applied. Spatially constrained inversion (SCI), joint inversion with P-wave travel times and tomography represent possible techniques to apply to retrieve 2D models.

A case history is reported to outline a possible strategy for the construction of a pseudo-2D model of shear-wave velocity for seismic site response studies. Experimental data have been collected using the Multichannel Analysis of Surface Wave technique (MASW) at six sites in the city of Najaf (Southern Iraq). The sites are aligned along the route of a proposed subway. The dataset has been processed to extract the dispersion curves of each site and then it has been inverted by using a Laterally Constrained Inversion (LCI) algorithm. The initial model for the local search algorithm has been obtained with a preliminary Monte Carlo Inversion (MCI). A priori information from borehole logs and lateral constraints between neighbors 1D models are used to mitigate the non-uniqueness of the solution. The result is a pseudo-2D shear-wave velocity model of the area which is in good agreement with sediment lithology and thicknesses obtained from borehole logs.

Combining S-wave data, resulting from surface-wave dispersion analysis with P-wave tomographic data, is a valuable tool to improve the understanding of near-surface soil properties and allows the estimation of soil mechanical parameters and the determination of the depth of the water table. To achieve this combination of methods in a complex fault zone setting, active-source seismic data were acquired at Inchbonnie, New Zealand across the Alpine Fault. This is a major transpressional strike-slip fault that has generated magnitude > 7.8 earthquakes in the past. In this study, we focus on the surface-wave component of these data, to determine elastic parameters for the shallow (~60 m) subsurface as well as the depth of the water table. We achieve this by combining S-wave velocity models from surface-wave dispersion curve inversion and P-wave velocity models obtained from traveltime tomographic inversion in a previous study. The surface-wave dispersion curve inversion is done by means of a laterally constrained inversion algorithm. As a result, we are able to obtain elastic parameters and map the water table and the geology around the Alpine Fault at Inchbonnie, New Zealand. The Alpine Fault itself appears as a relatively sharp lateral discontinuity in all investigated parameters.

We present an algorithm for the joint inversion of surface wave, P-wave refraction ad apparent resistivity data. The algorithm solves the model parameters imposing the same earth structure as well as the respect of some petrophysical relationships. P- and S-wave velocities are linked to each other through the Poisson's ratio in order to avoid unrealistic values. Moreover, for layers made of saturated porous media, both seismic velocities and the soil resistivity are further constrained by using rock physics relationship and imposing a common value of porosity. The final model is thus internally consistent not only in term of geometry but also in terms of physical properties. A synthetic example is provided. Individual inversions of each set of data are compared both to a structural joint inversion, where no physical links are applied, and to the full joint inversion in which physical constraints are imposed. While the individual inversions fall in local minima far from the correct solution, the structural joint inversion supplies a very good final model that is further refined applying the physical links. Finally, since the seismic velocities and the resistivity of the saturated layer are solved imposing the convergence to the same value of porosity, this parameter represents an additional result of the joint inversion algorithm

We present here a joint-inversion algorithm to build a resistivity, P-wave, and S-wave velocity model from apparent resistivity, surface wave dispersion and P-wave refraction data. This algorithm can also include a-priori information available for the site, as well as any physical links among the model parameters, and the result is an internally consistent multi-parametric model. The obtained model resolves more properly the true model because the joint inversion mitigates some problems related to the individual inversion of each type of experimental data like solution non-uniqueness, illness, or lack of resolution, which might lead to interpretation ambiguities. We describe the proposed algorithm and we show the result of its application on a smoothly laterally varying synthetic model.

Ground roll and mud roll in seismic reflection data can be analysed to infer a near surface S-wave velocity model from which converted-wave static correction can be computed. A workflow that exploits processing tools available in industrial processing codes has been implemented to extract dispersion curves and related uncertainties along a seismic line. The dispersion curves are then inverted with a laterally constrained inversion algorithm based on an initial model previously determined through a Monte Carlo inversion. The final S-wave velocity models are finally used for static computation. The application of the method to synthetic data supplied static correction values with error lower than 5%

The InterPacific (Intercomparison of methods for site parameter and velocity profile characterization) project aims to assess the reliability/variability of seismic site characterization methods (borehole and surface wave methods) used for estimating shear wave velocity (Vs) profiles and corresponding lumped parameters (e.g., Vs,30). The ultimate goal of the project is to determine procedures that can be used for the construction of consistent ground models for seismic studies. Three sites have been selected in France and Italy for the implementation of the project. They are representative of different geological conditions relevant for the evaluation of seismic site response effects: a stiff rock outcrop, a deep soft deposit, and an intermediate case with thick stiff soils and large bedrock depth.

The archaeological researches and more generally the Cultural Heritage (CH) documentation and conservation activities have been favourably disposed to the use of new technologies, with renewed and increasing interest in the use of integrated techniques. In the field of Geomatics the advent of advanced technologies has allowed and facilitated multidisciplinary studies as well as combined approaches to the documentation in various contexts. The production of spatially located data (e.g. from active or passive sensors placed in different system segments, from terrestrial to aerial to satellite position) and their interoperability from different source, with the help of Geographic Information Systems (GIS), were then made easier. The work has the aim of investigating the integration of multiple data derived from aerial photogrammetry products through Unmanned Aerial Vehicles (UAV) survey, from geophysical Ground Penetrating Radar (GPR) prospection technique and analysis of historical ma ps. An archaeological area in the south of Piedmont (Italy), next to the ancient Roman settlement of Pollentia, has been the test case. The present fulfilled test was objected to exclude ancient presences, although this type of workflow is generally aimed to analyse and compare results in order to formulate some hypothesis about the potential presence of submerged elements or built substructures in the investigated area