Cécile Cornou

University Joseph Fourier - Grenoble 1 | UJF · Institut des Sciences de la Terre (ISTerre)

The estimation of seismic damages and debris at the urban scale - at a precise building-by-building level- is challenging for several reasons. First, commonly used methodologies for seismic damage estimation rarely take into account the local site effects, precisely at the building-level. Second, the available methods for debris estimation fail to...

Since the 2000s, local seismic hazard studies have shown that Mayotte Island presented superficial geological formations prone to lithological site effects. The seismic sequence initiated in May 2018 confirmed the importance of such effects, both in terms of intensity and spatial extension. The analysis of the recorded strong motions showed that we...

The single-station microtremor horizontal-to-vertical spectral ratio (MHVSR) method was initially proposed to retrieve the site amplification function and its resonance frequencies produced by unconsolidated sediments overlying high-velocity bedrock. Presently, MHVSR measurements are predominantly conducted to obtain an estimate of the fundamental...

Microtremor array measurements, and passive surface wave methods in general, have been increasingly used to non-invasively estimate shear-wave velocity structures for various purposes. The methods estimate dispersion curves and invert them for retrieving S-wave velocity profiles. This paper summarizes principles, limitations, data collection, and p...

Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site conditions of the local geology. Thus, a number of geophysical site characterization methods were developed to meet the demand for accurate and cost-effective results. As a consequence...

Already sensitive because of its geology (seismic-tsunamic risk) and its interface between arid and temperate ecosystems, the Mediterranean Basin is being transformed by climate change and major urban pressure on resources and spaces. Lebanon concentrates on a small territory the environmental, climatic, health, social and political crises of the M...

Lebanon is a densely populated country crossed by major faults. Historical seismicity shows the potential of earthquakes with magnitudes >7, but large earthquakes have never been instrumentally recorded in Lebanon. Here, we propose a method to simulate near-fault broadband ground motions for a potential Mw 7 earthquake on the Yammouneh fault (YF)—t...

In recent years, the permanent seismic networks worldwide have largely increased, raising the amount of earthquake signals and the applications using seismic records. Although characterization of the soil properties at recording stations has a large impact on hazard estimates, it has not been implemented so far in a standardized way for reaching hi...

Many applications related to ground-motion studies and engineering seismology benefit from the opportunity to easily download large dataset of earthquake recordings with different magnitudes. In such applications, it is important to have a reliable seismic characterization of the stations to introduce appropriate correction factors for including si...

During the 3 rd ESG symposium held in Grenoble in 2006, the Grenoble valley was the target of a verification exercise of physics-based methods for ground motion prediction including site effects. Back then, knowledge of the velocity model was limited to large depths and prevented the application of 3D numerical simulation for frequencies higher tha...

The spatial incoherence of ground motion during an earthquake can have a significant effect on the dynamic response of engineering structures such as bridges, dams, nuclear power plants and lifeline facilities. The main objective of this paper is to study the effect of anisotropic heterogeneities in a soil layer overlying homogeneous bedrock on the...

Traditional seismic risk assessment approaches focus on assessing the damages to the urban fabric and the resultant socioeconomic consequences, without adequately incorporating the social component of risk. However, the behaviors people adopt in response to earthquakes, affect their exposure to the threat, and should be considered in quantitative r...

Impact of the 4th of August 2020 Beirut, Lebanon, port explosion on dynamical building properties

An unusually damaging Mw 4.9 earthquake occurred on November 11, 2019 in the south east of France within the lower Rhône river valley, an industrial region that hosts several operating nuclear power plants. The hypocentre of this event occurred at an exceptionally shallow depth of about 1 km. Here we use far-field seismological observations to demo...

On November 11, 2019, an unusually damaging Mw4.9 earthquake occurred in the south east of France within the lower Rhône river valley, an industrial region hosting several operating nuclear power plants. This event is exceptional considering its very shallow depth (<1 km). Based on farfield seismological observations, we demonstrate that the ruptur...

Effects of seismic ground motion induced by surface geology and geometry are known to be associated with the generation of a substantial proportion of surface waves. As a consequence, surface waves significantly contribute to ground-motion variability and site amplification. There is a growing body of literature recognizing that an understanding of...

Most seismic risk assessment methods focus on estimating the damages to the built environment and the consequent socioeconomic losses without fully taking into account the social aspect of risk. Yet, human behaviour is a key element in predicting the human impact of an earthquake, therefore, it is important to include it in quantitative risk assess...

On November 11, 2019, a Mw 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to...

On November 11, 2019, a Mw 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to...

Empirical ground motion prediction equations are calibrated from past earthquake seismic recordings. Although they are often used to predict Peak Ground Acceleration (PGA) and its variability, the use of these equations to predict near-fault PGA remains questionable due to the scarcity of near-fault recordings for large earthquakes (e.g. Mai Encycl...

Ambient vibrations are nowadays considerably used worldwide for numerous types of engineering applications and scientific research. Geopsy and its companion tools are part of that landscape. Since the first release of the program package in 2005, as outcome of the European Union project Site Effects aSsessment from AMbient noisE, Geopsy has become...

Difficulties with geographical boundaries are well known in the field of macroseismicity, while the ones of "temporal boundaries", that correspond to changes in the type of documentary sources over time is less often studied. Documentary corpus evolution with time lead to manipulation of heterogeneous data (both in terms of quantity and quality), a...

This work is a multidisciplinary approach from geological and geophysical surveys to build a 3D geological model of Argostoli Basin (Cephalonia Island, Greece) aiming to be used for computational 3D simulation of seismic motion. Cephalonia Island is located at the north-western end of the Aegean subduction frontal thrust that is linked to the dextr...

Experimental assessment of spatial variability and numerical tests What comes next? • Construction of metamodels for a couple of scenarios (M4,5,6) to represent ground motion for regional risk assessment • Computation of fragility curves EFISPEC3D simulations Site characterization • Geological data  soil columns • Identification of statistical sit...

Artificial neural networks are trained, using a large set of data, to find relations that estimate buildings’ earthquake damages, from simple indicators describing the seismic shaking level and the soils’ and buildings’ vibrational properties These relations are applied to estimate probable damages in the city of Beirut, Lebanon, for different seis...

Des réseaux de neurones artificiels sont entrainés, par un large jeu de données, à trouver des relations qui estiment l'endommagement des bâtiments suite aux séismes, à partir d’indicateurs simples décrivant le niveau de sollicitation sismique et les propriétés vibratoires du sol et des bâtiments Ces relations sont utilisées afin d’estimer les domm...

Spatial variability of earthquake ground motion (SVEGM) refers to the differences in amplitude and phase between recordings of the same earthquake at different locations. In the near-surface, geological processes (se-dimentation, erosion) and anthropogenic activities can lead to small scale spatial heterogeneities of soil mechanical properties, whi...

There have been over last decades several examples of large ground vibrations caused by masses of people gathered for special events: a rock concert in Ullevi stadium (Gothenburg, Sweden) in 1985 generated strongly felt tribune vibrations, while there are repeated examples of seismological recordings corresponding to goals in high stake soccer matc...

Lebanon is situated on the 1000 km long Levant transform fault that separates the Arabic from the African tectonic plates. In Lebanon, the Levant fault splits up into a set of ramifications that had, in the past, generated major destructive earthquakes causing a lot of destruction and thousands of casualties. The most devastating one was the 551 A....

Result from ambient noise measurement on building in Tehran,Iran

The term “spatial variability of seismic ground motions” denotes the differences in the amplitude and phase content of seismic motions. The effect of such spatial variability on the structural response is still an open issue. In-situ experiments may be helpful in order to answer the questions regarding both the quantification of the spatial variabi...

The stochastic estimation of coherency is perceived, in some studies, to be significantly influenced by the time window length under consideration. For the engineering purposes, usually, coherency is estimated from the strong motion, i.e., the shear (S-) wave segment of the recorded time series. However, the identification of a purely S-wave domina...

Recordings from two dense arrays deployed at Argostoli, Cephalonia Island, Greece, are analyzed with three objectives: (1) exploring to what extent the diffracted surface waves influence the seismic wavefield at a rock site, (2) investigating the loss of coherency of ground motions, and (3) comparing the results for two nearby sites with different...

The site for experimental assessment of spatial variability at local scale is the Argostoli basin situated in the Cephalonia Island in Western Greece. This site has been extensively instrumented over the last years within the framework of EU NERA (2011-2014) and ANR SINAPS@ (2014-2018) projects. More specifically, a dense seismological experiment c...

Nakamura (Q Rep Railway Tech Res Inst 30:25–33, 1989) popularized the application of the horizontal-to-vertical spectral ratio (HVSR) analysis of microtremor (seismic noise or ambient vibration) recordings to estimate the predominant frequency and amplification factor of earthquake shaking. During the following quarter century, popularity in the mi...

The variation of Rayleigh ellipticity versus frequency is gaining popularity in site characterization. It becomes a necessary observable to complement dispersion curves when inverting shear wave velocity profiles. Various methods have been proposed so far to extract polarization from ambient vibrations recorded on a single three-component station o...

Soil spatial variability is modeled using random fields (RF) theory. Discretization based on series expansion methods is generally adopted to evaluate the RF of a soil property. Several realizations are generated randomly to represent the statistical distribution of the soil parameter. However, not all of them represent the real variability. Thus,...

Spatial incoherence of earthquake ground motion (SIEGM), modelled by a “coherency function”, can have significant effect on the dynamic response of engineering structures such as bridges, dams, nuclear power plants, and lifeline facilities. This paper deals with the study of near-surface heterogeneities effect on the coherency of surface ground mot...

Data provided by accelerometric networks are important for seismic hazard assessment. The correct use of accelerometric signals is conditioned by the station site metadata quality (i.e., soil class, VS30, velocity profiles, and other relevant information that can help to quantify site effects). In France, the permanent accelerometric network consis...

Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the VS,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standa...

French National Research Project ANR EXAMIN

The spatial variation of the earthquake ground motion over short distances can significantly affect the dynamic response of large and extended engineered structures, especially on sites with inhomogeneity in surface geology and geometry. In current practices, such variation is taken into account in terms of coherency, a function of frequency and di...

Landslides represent a serious threat to human life and activities in most mountainous areas. However, due to the rugged nature of such terrain, it is often difficult to detect such phenomena in remote areas. Hence, satellite imagery offers many attractions for the examination of landslides in such environments, especially in less developed nations...

Two very dense seismographic arrays were deployed in a seismically active area in Greece to incorporate the difference in amplitude and phase be-tween two stations located within the dimension of a structure. The spatial variability in seismic ground motion is generally attributed to the wave passage effect, the incoherence effect and the local sit...

In this study data and results of a high-resolution experiment in Cephalonia (Greece) regarding empirical basin effects are presented. A total of 59 velocimeters and 17 accelerometers were deployed in the basin of Argostoli Cephalonia (Greece), for a period of 7 months (September 2011–April 2012). Due to high seismicity of the western Greece and su...

Cephalonia Island is one of the most seismic zones of the Euro- Mediterranean area due to the activity of the Cephalonia transform fault connecting the Hellenic subduction to the northwest Greece collision. Following the two Mw 6+ earthquakes that occurred in early 2014, a postseismic survey was organized within the framework of the [email protecte...

Post-seismic investigations repeatedly indicate that structures having frequencies close to foundation soil frequencies exhibit significantly heavier damages (Caracas 1967; Mexico 1985; Pujili, Ecuador 1996; L’Aquila 2009). However, observations of modal frequencies of soils and buildings in a region or within a current seismic risk analysis are no...

The ground velocity pulses generated by rupture directivity effects in the near-fault region can cause a large amount of damage to structures. Proper estimation of the period of such velocity pulses is of particular importance in characterizing near-fault seismic hazard and mitigating potential damage. We propose a simple equation to de- termine th...

Spatial variability of earthquake ground motion (SVEGM) refers to the differences in amplitude and phase between recordings of the same earthquake at different locations. SVEGM can have a significant effect on the dynamic response of large structures with large dimensions, such as dams, nuclear power plants, bridges and lifeline facilities. Usually...

Resonance period is a key parameter in the seismic design of a structure, thus dynamic parameters of buildings in Beirut (Lebanon) were investigated based on ambient vibration method for risk and vulnerability assessment. Lebanon is facing high seismic hazard due to its major faults, combined to a high seismic risk caused by dense urbanization in a...

In order to assess repeatability and time stability of surface waves dispersion estimates, seismic ambient noise have been recorded during 6 months by a 21-element broad band seismological dense array deployed in the small size alluvial basin of Argostoli,Greece. Then environmental effects and noise sources azimuthal distribution has been considere...

Post-seismic investigations repeatedly indicate that structures having frequencies close to foundation soil frequencies exhibit significantly heavier damages (Caracas 1967, Mexico 1985, Pujili, Ecuador 1996; L'Aquila 2009). However, these observations are generally not taken directly into account, neither in present-day seismic regulations (small s...

The non-linear behavior in soft to moderately stiff soils modifies the linear site response, generally by shifting the resonance frequencies towards lower values, and reducing the high-frequency motion in relation to shear modulus decrease and damping increase with increasing loading. The resulting " modulation " of the site response may be quantif...