Manuela Villani

• PhD in Engineering Seismology and Earthquake Engineering
• Arup

Over the last twenty years numerous destructive earthquakes have had a significant impact in the region and specifically on the populations of Gujarat, Kashmir and Kathmandu. This has led the academic community to develop and publish numerous seismic hazard studies within the region. The most notable is the GEM map, which is based on Nath et al., (...

Following the 2019 incident on the auxiliary spillway at Toddbrook Reservoir the stability of the embankment dam was assessed. One of the findings was to assess the seismic performance of the embankment, including stress deformation analysis to estimate likely displacements. In collaboration with the Canal & River Trust and the All Reservoir Panel...

The current practice of probabilistic seismic hazard analysis (PSHA) does not take into account that earthquakes actually occur in time-space clusters. The input for PSHA is based on declustered seismic catalogs, used to characterize only the mainshocks, that is, the largest magnitude events within each cluster. However, the so-called sequence-base...

In probabilistic seismic hazard assessment, the development of the seismic source characterization, especially the geometry of the seismic source models (SSMs), is controversial because it often relies on expert judgment with different interpretations of the available data from seismology, tectonics, and geology. Based on the same input datasets, d...

The United Kingdom (UK) is a region of low-to-moderate seismicity where seismic design is only required for strategic facilities such as nuclear power plants [4]. Arup, appointed by Horizon Nuclear Power, carried out a seismic hazard assessment for the Wylfa Newydd site, which included capable fault assessment, tsunami hazard, probabilistic seismic...

This study presents the probabilistic seismic hazard assessment (PSHA) for a nuclear site in the UK, Wylfa Newydd. The PSHA was defined at a bedrock horizon with shear wave velocity of 3000 m/s and developed to capture the centre, body and range of the technical defensible interpretations. Although not a formal SSHAC (Senior Seismic Hazard Assessme...

This paper presents an overview of the seismic hazard assessment commissioned by Horizon Nuclear Power for the Wylfa Newydd site. The project was developed to utilise both UK experience and aspects of the Senior Seismic Hazard Analysis Committee (SSHAC) approach, including facilitation and independent peer review. The project aimed to assess the po...

A seismic hazard assessment was performed for the Wylfa Newydd Nuclear Power Plant following the US Regulatory guidelines for nuclear facilities, which require a probabilistic seismic hazard assessment at an outcropping bedrock alongside a probabilistic site response analysis incorporating the epistemic uncertainty due to the inherent heterogeneity...

The UK is a relatively low seismicity region and therefore seismic design is applied only to high consequence facilities, e.g. nuclear power plants. Knowledge of the tectonic structures beneath the UK is limited and the earthquake catalogue covers a relatively short history compared to the geological history. In this context, the definition of the...

Good practice for defining the surface response spectra (RS) in a seismic hazard assess-ment often requires two steps: a probabilistic seismic hazard assessment (PSHA) at bed-rock level and a site response analysis (SRA) that accounts for the amplification of the near surface deposits. The soil profile is typically modelled accounting for its varia...

In countries with low‐to‐moderate seismicity, the selection of appropriate ground‐motion prediction equations (GMPEs) to be used in a probabilistic seismic hazard analysis (PSHA) is a challenging step. Empirical observations of ground motion are limited, and GMPEs, when available, are generally based on stochastic simulations or adjusted empirical...

This paper contains 3D/2D/1D ground response analyses of Norcia basin during the M6.5 2016 October 30 event by comparing the recorded response at NOR and NRC stations, which are located in mid-basin and near-fault conditions. Results show that 3D simulations may capture the overall response reasonably well, yet the simplification of vertical incide...

West Africa is considered to be a region of low seismicity, yet in spite of this, the region has experienced destructive historical earthquakes such as the 1939 Accra, Ghana earthquake which killed 22 people and left about 130 injured. Today, parts of Ghana, Nigeria and Cameroon continue to experience moderate and smaller magnitude earthquakes, hig...

In an effort to incorporate building fragility into seismic risk assessment, simple formulations of fragility functions are developed, such as a cumulative lognormal distribution, which describe the probability of damage of a building experiencing a given ground motion. We show here that when a lognormal fragility function is empirically estimated...

In this study, we use two sets of residuals of the response spectral values to identify the repeatable effects due to specific ray paths and sites that are generally included in the standard deviation of the ground-motion prediction equations (GMPEs): one empirical set of residuals from the Abrahamson et al. (2014) GMPE and one set derived from sim...

This work proposes a novel approach for probabilistic seismic hazard analyses (PSHA) in the near field of active earthquake faults, in which deterministically computed ground motion scenarios, replacing empirically predicted ground motion values, are introduced. In fact, the databases of most ground motion prediction equations (GMPEs) tend to be in...

It is our belief that as engineers, geologists, seismologists, architects and designers we have the responsibility to improve the world's infrastructure, so that the world becomes a more resilient place to live. Too often we take the easy option of " doing what the code says " and not thinking about how we can improve the status quo. This is import...

A numerical study on the 2009 M-w 6.3 L'Aquila earthquake is here presented using a high-performance spectral element (SE) code to clarify the issues regarding the generation of physics-based deterministic ground-motion scenarios in near-fault conditions and over a broad range of frequencies. Numerical simulations provide reliable ground-motion sce...

This study aims at investigating the influence of the application of low pass acausal Butterworth filters on the derived GMPEs at short periods. To this end, the original time-histories of the Cauzzi and Faccioli (2008), CF08, database, with no correction at high frequency, are used. Four sets of GMPEs are derived after the application of a low-pas...

The Italian Garigliano Nuclear Power Plant (NPP) started its energy production in 1963. At present it is in the decommissioning stage. In order to get a proper management of the radioactive waste that will be produced during the dismantling operations it has been considered convenient to convert the turbine building of the plant into a temporary wa...

Yamada et al. (2009) collected recorded ground motions from the near-source region of large earthquakes that occurred before 2005 and investigated to what extent this historical record could provide a basis for estimating future ground motions at similar sites. Their main conclusion, which they refer to as a paradox, is that the largest peak ground...

Within the framework of an ongoing Italian research project (INGV-DPC S2), aimed at developing a dynamical model for seismic hazard assessment at national scale, a research task is devoted to broadening the options for site effects by means of including topographic amplification factors in ground motion prediction equations. The paucity of signific...

Displacement-based design applied to a broad class of structures, including large bridges and very tall buildings, requires that seismic hazard be mapped in terms of displacement response spectra (DRS) up to long vibration periods. An appropriate hazard representation is presented herein for Italy, in an improved version with respect to a recently...

A new representation of seismic hazard is proposed for Italy based on displacement elastic response spectra in a vibration period range that extends from 0 s to 20 s. This relies on an available seismotectonic zonation and earthquake catalogue, but makes use of a set of very recent, expressly developed attenuation relations. The long period picture...

The reliability of long-period ground motion from digital strong motion data is first explored using records from co-located broadband and digital strong motion instruments. It is shown that displacement waveforms obtained by double integration of the accelerogram need not be free of unrealistic baseline drift to yield reliable spectral ordinates u...

Consistently with the use of seismic inertia forces for the verification of structural members, buildings have been traditionally designed for earthquake resistance by relying on ground acceleration from strong earthquakes to describe seismic loading; in most applications this is quantified by acceleration response spectra. However, structural desi...

The reliability of long-period ground motion from digital strong motion data is first explored using records from co-located broadband and digital strong motion instruments. It is shown that displacement waveforms obtained by double integration of the accelerogram need not be free of unrealistic baseline drift to yield reliable spectral ordinates u...

The effects of the seismic source and of local geology on ground motion are studied in the Upper Soa Valley (western Slovenia), which was struck by two earthquakes, on 12 April 1998 (MW=5.6) and on 12 July 2004 (M W=5.2). The paper focuses on the latter event, while the former was thoroughly investigated in Gosar et al. (2001). 2D numerical modelli...

The study illustrates probabilistic ground shaking hazard analyses and risk assessment in the near field of a rupturing earthquake fault, where the datasets underlying most ground motion predictive equations (GMPEs) tend to provide insufficient coverage. In order to overcome this limitation, explicit modeling of source and wave propagation at the s...