Agathe Roullé

French Geological Survey | BRGM · Direction Risques et Prévention

A new marine volcano is erupting offshore Mayotte since May 2018, generating numerous earthquakes. The population felt many of them and the stronger shaking of the ongoing sequence caused slight damage to buildings. Historical records also confirm that damaging earthquakes had occurred in the past in this region. Seismic damage scenarios are a key...

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 brutal onset of seismicity offshore Mayotte island North of the Mozambique Channel, Indian Ocean, that occurred in May 2018 caught the population, authorities, and scientific community off guard. Around 20 potentially felt earthquakes were recorded in the first 5 days, up to magnitude Mw 5.9. The scientific community had little pre-existing kno...

This article studies the effects of the soil data and exposure data of residential building inventories, as well as their spatial resolution, on seismic damage and loss estimates for a given earthquake scenario. Our aim is to investigate how beneficial it would be to acquire higher resolution inventories at the cost of additional effort and resourc...

Rapid estimation of the intensity of seismic ground motions is crucial for an effective rapid response when an earthquake occurs. To this end, maps of updated grond-motion fields (or shakemaps) are produced by using observations or measurements in near real-time to better constrain initial estimates. In this work, two types of observations are inte...

On May 10th, 2018, an unprecedented long and intense seismic crisis started offshore, east of Mayotte, the easternmost of the Comoros volcanic islands. The population felt hundreds of events. Over the course of one year, 32 earthquakes with magnitude greater than 5 occurred, including the largest event ever recorded in the Comoros (Mw = 5.9 on May...

The Mexico City valley is a paradigmatic example of an alluvial structure generating large ground motion amplification and energetic low frequency waves. Through observations and numerical simulations researchers have established that the seismic field in the Mexico City valley is mainly composed of surface waves, and the discussion of their role i...

This study describes the development of the various components of the European Seismic Risk Model 2020 (ESRM2020) which will be able to generate, using open-source software developed by the GEM Foundation (the

On 2018 May 10, a seismic crisis started ~50 km east of Mayotte, the easternmost of the Comoros volcanic islands. Here we analyze its first six months, from 2018 May 10 to November 14. In that period, 29 earthquakes with magnitude greater than 5 occurred, the main one reaching Mw = 5.9 on 2018 May 15. In mid November, the crisis was continuing with...

The Mayotte island (Indian Ocean, Comoros archipelago) is undergoing an exceptional offshore volcano-tectonic seismic crisis which started May 10th, 2018, peaked with a magnitude Mw5.9 on the 15th of the same month, and has produced more than two thousand M4+ events to date (Bertil 2019). To monitor this crisis, since February 2019, several French...

In this paper, we describe recent studies for the geophysical and geomechanical characterization of soils in Hispaniola (Greater Antilles), an island threatened by the eventual rupture of major seismogenic fault systems. The investigations were performed for four different cities settled on complex geological formations in Haiti (Cap-Haïtien, Port-...

List of 347 earthquakes with Magnitude >=4.0 detected with the Accelerometer station YTMZ (RESIF-RAP station at Mayotte) and pga from the horizontal components at YTMZ. Magnitude estimate from pga.

List of 347 earthquakes from Mayotte earthquek swarm with Magnitude >=4.0 detected with the Accelerometer station YTMZ (RESIF-RAP station at Mayotte) and pga from the horizontal components at YTMZ. Magnitude estimate from pga.

Detection and location of seismic events during Mayotte swarm, May 10th 2018 – July 26th 2018

list of 347 earthquakes with Magnitude >=4.0 detected with the Accelerometer station YTMZ (RESIF-RAP station at Mayotte) and pga from the horizontal components at YTMZ. Magnitude estimate from pga

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...

Tras el terremoto de Haití de 2010 dio comienzo una iniciativa para estudiar los posibles efectos de los terremotos en la ciudad de Santiago de los Caballeros (República Dominicana); la segunda ciudad más importante del país y que ya fue reconstruida y reubicada en 1562. El daño debido a un terremoto ocurre asociado a un conjunto de factores, entre...

The uncertainty involved in localizing geothermal reservoirs has been a significant impediment in the exploitation of potential geothermal energy. More research is needed to explore imaging tools in order to characterize the first few kilometers of the subsurface. In parallel to a multidisciplinary approach, ability of teleseismic earthquakes’ wave...

After the Haiti quake of 2010 an initiative started to better understand shaking effects in the Dominican Republic after natural earthquakes, in particular in the city of Santiago de los Caballeros, the second city in the country as far as inhabitants and economic wealth are concerned. Santiago has suffered several devastating earthquakes; in 1562...

Haïti cherche à mettre en place un code national de construction, le CNBH, qui s'appuie sur le code international IBC avec une classification des sols et des coefficients d'amplifications Fa et Fv suivant les recommandations NEHRP. Des microzonages sismiques effectués sur 5 des villes les plus exposées d'Haïti ont permis de caractériser 73 colonnes...

This article is concerned with attempting to ‘predict’ (hindcast) the damage caused by the L’Aquila 2009 earthquake (Mw 6.3) and, more generally, with the question of how close predicted damage can ever be to observations. Damage is hindcast using a well-established empirical-based approach based on vulnerability indices and macroseismic intensitie...

A seismic microzoning was performed for Cap Haitien city in Haiti. This city is as much exposed to seismic hazard as Port-au-Prince struck by the January 2010 earthquake. Many complementary investigations in geology, geophysics and geotechnics were needed to define areas of homogeneous soil response. The cross-analysis of this information allowed u...

After the earthquake of January 12, 2010 in Haiti, the Haitian Government has resolved to implement a program of seismic microzonation for most vulnerable cities in the country by the way of prevention. Metropolitan Port-au-Prince and five cities in the North of Haiti including Cap-Haitien were included in this program. The seismic microzonation is...

: Within the SISPYR project, a seismic risk evaluation is presented for a cross-border zone in the Pyrenees (Saint-Beat and Luchon in France and the Val d'Aran in Spain). This area has been selected because of recent seismic activity and the importance of tourism in this region. The vulnerability of existing buildings is assessed by using the vulne...

The magnitude 7.3 earthquake that struck Haiti in January 12, 2010 has caused a lot of damages in surrounding areas epicenter. These damages are due to a lack of knowledge of the Haitian subsoil. To overcome this problem, the LNBTP, the BME and BRGM have agreed to implement a project of seismic microzonation of the metropolitan area of Port-au-Prin...

The vulnerability of structures subjected to dynamic actions has been a very active field of research in recent years. In particular, the use of ambient response recording aims to improve our knowledge about the dynamic behaviour of structures, and the interferometric Real Aperture Radar (RAR) technique has recently emerged as a promising tool for...

Over recent years, many studies devoted to large-scale seismic risk analyses have been carried out in different regions and by various research teams. A wide variety of software is available to perform these analyses: they are more or less flexible and use different levels of precision to model ground motion and vulnerability of the built environme...

For Spain and France, Pyrenees are one of the most active seismic zones. Seismic risk mitigation is then a priority in this area. In this context, European project SIPYR aimed at developing rapid response systems to help planning emergency interventions in case of major seismic crisis. One of the developed tools for seismic risk mitigation is seism...

A comprehensive review of seismic studies undertaken by the French Geological Survey within the Caribbean region

Vulnerability of structures exposed to dynamic actions is a very active domain research for the last years. Seismic background noise measurement networks should improve our knowledge on the dynamic behaviour of structures. In order to determine the modal characteristics (eigenfrequencies, vibration eigenmodes, and damping) of a building in reinforc...

RÉSUMÉ. L'objectif de cette étude est de réaliser des simulations réalistes de séismes à grande échelle et haute fréquence (environ 5 Hz) dans la région de Pointe-à-Pitre, Guadeloupe. Pour cela, une modélisation détaillée de la source sismique et de la structure de vitesse du milieu est nécessaire. La géologie locale a été construite via le logicie...

The goal of this study is to perform realistic large-scale spectral-element simulations in the vicinity of Pointe-à-Pitre, valid up to rather high frequencies (around 5 Hz) with a minimal shear-wave velocity around 200 m/s and considering magnitude 5 to 6 earthquakes. For this purpose, a detailed modeling of both the seismic source and geology of t...

In order to propose methodological solutions for reducing seismic risk in Caribbean urban zones, efforts concentrate on applying research activities. For example, elaborating seismic risk scenarios allows a better assessment of the consequences of an earthquake affecting the organization of social structures, in order to highlight sensitive sectors...

Spatial variability of ground motion may be explained by local soil conditions; it is the so-called "site effects". Site effects are responsible for increasing duration and important amplification of strong ground motion during earthquakes and must be considered as a key parameter in local seismic hazard assessment. French West Indies are prone to...

Observations from many recent strong motion events have shown the importance of local soil conditions and non-linear soil behaviour on the seismic ground response (site effects). As demonstrated by previous seismic microzoning studies (Lebrun et al.) [1]), as well as by at least three historical major earthquakes, Pointe-à-Pitre is prone to strong...

Using several geophysical methods to better constrain a diagnosis is a standard approach in many field studies. Generally data of each method are individually inverted and a global geological / hydro-geological interpretation is realized as a second step from separated inversion results. Thereby, contributions and limitations of each method to fina...

Scénario départemental de risque sismique Méthodologie et processus de réalisation Rapport final BRGM/RP-55415-Fr to be cited like this: SEDAN O., TERRIER M., NEGULESCU C., WINTER T., DOUGLAS J., ROULLE A., ROHMER J., S. BESDE- BERC, C., DE MARTIN F., ARNAL C., DEWEZ T., FONTAINE M. (2008) - Scénario départemental de risque sismique- Méthodologie...

The pilgrimage city of Lourdes in the French Pyrenees has been heavily damaged by earthquakes in the seventeenth and eighteenth centuries. Assessments of local seismic hazard have been performed through a seismic microzonation of the city. A campaign of urban noise recording has been conducted at about 180 points to determine seismic wave amplifica...

An extensive S-wave velocity survey had been carried out in the frame of a recent seismic microzonation study of Basel and the border areas between Switzerland, France and Germany. The aim was to better constrain the seismic amplification potential of the surface layers. The survey included single station (H/V spectral ratios) and ambient vibration...

Strong-motion networks have been operating in the Caribbean region since the 1970s, however, until the mid-1990s only a few analogue stations were operational and the quantity of data recorded was very low. Since the mid-1990s, digital accelerometric networks have been established on islands within the region. At present there are thought to be abo...

In 2001, we installed 11 new accelerometers in the lake-bed zone of Mexico City, which, together with the existing stations, form a 3D array of small aperture, with 15 surface and six borehole stations. This new array recorded the 10/08/2001 Guerrero event (M=6.1) and the 01/22/2003 Colima (M=7.6) event. The analysis of these two events showed that...

Observed seismic motion in the lakebed zone of the Valley of Mexico is complex because of thelarge epicentral distance, an irregular 3D crustal structure, large noise levels, strong site effects, andthe possible presence of mixed modes and multipathing. These conditions tax the possibilities of thearray-processing techniques. In this paper, we test...

Site response at Mexico City has been intensively studied for the last 15 years, since the disastrous 1985 earthquakes. After those events, more than 100 accelerographs were installed, and their data have been extremely useful in quantifying amplification and in the subsequent upgrading of the building code. However, detailed analysis of the wavefi...

2) , Sara Figueras (2), Daniel Monfort-Climent (1) , Nieves Lantada (3) , Teresa Susagna (2) and Janira Irizarry (2) (1) BRGM -Bureau de Recherche Géologique et Minière, Orléans (France).

2) Bureau de Recherches Géologiques et Minières (BRGM) (3) Antes en el BRGM (4) Centre de Recerca en Ciències de la Terra de l'Institut d'Estudis Andorrans (CRECIT) amacau@igc.cat RESUMEN En el marco del proyecto ISARD (Información Sísmica Automática Regional de Daños) se han seleccionado los valles de la Cerdaña y de Andorra la Vella como zonas pi...