Municipal expected annual loss as an indicator to develop seismic risk maps in Italy

This work presents a risk-targeted indicator called Municipal Expected Annual Loss (MEAL) for a quantitative estimation of the seismic risk at territorial level. With MEAL, it is possible to calculate the impact of earthquakes in terms of direct losses, taking account of a wide set of earthquake scenarios on the built environment at municipal level. MEAL is, therefore, able to summarize scenario loss values of each municipality, and define in such a way a risk-targeted metric that can clearly be understood also by different stakeholders dealing with seismic risk management, mitigation, and transfer. The use of MEAL to map seismic risk for the Italian residential building stock is herein presented as a case-study, leading to the development of several maps able to depict seismic risk at different territorial scale levels

A New Asteroseismic Diagram For Solar-type Stars

We propose a new kind of seismic diagram, based on the determination of the locations of sharp acoustic features inside a star. We show that by combining the information about the position of the base of the convective envelope or the second helium ionisation zone with a measure of the average large separation, it is possible to constrain the unknown parameters characterising the physical processes in the stellar interior. We demonstrate the application of this technique to the analysis of mock data for a CoRoT target star.Comment: 2 pages, to appear in the proceedings of the "Stellar Pulsation and Evolution" conference, Monte Porzio Catone, June 200

Asteroseismic diagrams for solar-type stars

We explore the feasibility of applying the Christensen-Dalsgaard diagram to real asteroseismic data and provide quantitative measures of the uncertainty associated with the results. We also propose a new kind of seismic diagram, based on the determination of the locations of sharp acoustic features inside a star. We show that by combining the information about the position of the base of the convective envelope or the HeII ionisation zone with a measure of the average large separation, it is possible to constrain the unknown chemical composition or the various parameters characterising the physical processes in the stellar interior. We demonstrate the application of this technique to the analysis of mock data for a CoRoT target star.Comment: Accepted for publication in A&

Modelling of timber joints in traditional structures

Original unstrengthened timber connections and the effects of different strengthening techniques have been evaluated experimentally with tests on full-scale birdsmouth joints. Experimental results show that structural response of traditional timber connections under cyclic loading cannot be represented by common constraint models, like perfect hinges or rigid joints, but should be using semi-rigid and friction based models. A research program has investigated the behaviour of old timber joints and examined strengthening criteria. The main parameters affecting the mechanical behaviour of the connection have been singled out. A synthetic model of cyclic behaviour has been adapted on the basis of experimental results

Evaluation of seismic response trends from long-term monitoring of two instrumented RC buildings including soil-structure interaction

Peer reviewedPublisher PD

Application of passive seismic to the detection of buried hollows

Pilot studies involving the use of passive seismic techniques in a range of geological settings and applications, e.g., mapping bedrock, studies of soil erosion and Quaternary mapping have shown that it is a versatile, non-invasive and economic technique. This paper presents the findings of three case studies that trialled the use of passive seismic techniques for the detection and characterisation of buried hollows in carbonate rocks, comprising: i) a buried hollow in the Cretaceous Chalk at Ashford Hill in the Kennet Valley, a tributary of the River Thames, UK; ii) buried karst in the foundation excavations for wind turbines in Carboniferous Limestone at Brassington, Wirksworth, Derbyshire, UK, and iii) defining the extent of solution hollows that host terrestrial Miocene deposits, near Friden, Newhaven, Derbyshire, UK. Whilst case studies ii) and iii) are focused on areas of buried dolines, the geological context of the Ashford Hill site is more complex; comprising a deformation hollow with an uplifted “pinnacle” of chalk bedrock at the centre. The data were collected using a (Tromino), a three-component, broadband seismometer to measure background ambient noise (microtremors induced by wind, ocean waves, industrial machinery, road and rail traffic, etc.). The Tromino is small, portable with an operating range of 0.1 Hz to 1,024 Hz and interpreted using proprietary software (Grilla), which subjects the data to Fourier transformation and smoothing. Where possible, estimated shear wave velocities used in the Grilla Software modelling, based on peaks identified on the H/V spectrum, have been calibrated using borehole data or parallel geophysical techniques. In each case, the karst features were defined by Nakamura’s horizontal to vertical (H/V) spectral ratio technique, where microtremors are converted to show impedance contrasts (velocity x density), or a pseudo layered seismic stratigraphy of the near surface along each profile. An additional benefit of the use of this technique is its depth of penetration and potential for defining the structural and lithological context of the hollows, thereby contributing to the process understanding associated with their formation. To this end the technique has helped define discontinuity (fault, joint or bedding) guidance of the hollows.S. Castellaro, Mrs J. Renwick, West Coast Energy Ltd (GDF Suez), Mr Roger Durrant (Raymond Brown Construction Ltd

Estimating stellar mean density through seismic inversions

Determining the mass of stars is crucial both to improving stellar evolution theory and to characterising exoplanetary systems. Asteroseismology offers a promising way to estimate stellar mean density. When combined with accurate radii determinations, such as is expected from GAIA, this yields accurate stellar masses. The main difficulty is finding the best way to extract the mean density from a set of observed frequencies. We seek to establish a new method for estimating stellar mean density, which combines the simplicity of a scaling law while providing the accuracy of an inversion technique. We provide a framework in which to construct and evaluate kernel-based linear inversions which yield directly the mean density of a star. We then describe three different inversion techniques (SOLA and two scaling laws) and apply them to the sun, several test cases and three stars. The SOLA approach and the scaling law based on the surface correcting technique described by Kjeldsen et al. (2008) yield comparable results which can reach an accuracy of 0.5 % and are better than scaling the large frequency separation. The reason for this is that the averaging kernels from the two first methods are comparable in quality and are better than what is obtained with the large frequency separation. It is also shown that scaling the large frequency separation is more sensitive to near-surface effects, but is much less affected by an incorrect mode identification. As a result, one can identify pulsation modes by looking for an l and n assignment which provides the best agreement between the results from the large frequency separation and those from one of the two other methods. Non-linear effects are also discussed as is the effects of mixed modes. In particular, it is shown that mixed modes bring little improvement as a result of their poorly adapted kernels.Comment: Accepted for publication in A&A, 20 pages, 19 figure