Ground-Motion Simulations of the 2004 Mw 6.4 Les Saintes, Guadeloupe, Earthquake Using Ten Smaller Events

Courboulex, Françoise; Converset, Julien; Balestra, Julien; Delouis, Bertrand

doi:10.1785/0120080372

Cited by 13 publications

(11 citation statements)

References 41 publications

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“…The main-shock centroid moment tensor focal mechanism was taken from Courboulex et al (2010), and the radiation pattern coefficients were calculated using the equations given by Aki and Richards (2002).…”

Section: Do Source Radiation Patterns Explain the Observed Azimuthal mentioning

confidence: 99%

High-frequency directivity effects: evidence from analysis of the Les Saintes records

et al. 2014

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The main-shock (Mw, 6.3) and the aftershocks of the 'Les Saintes' earthquake sequence (French Indies) were analyzed to quantify highfrequency directivity effects. A correction method was applied to isolate source spectra within a large frequency range (0.5 to 25 Hz). Most of the aftershocks source spectra are fully consistent with a Brune spectrum pointsource shape and do not show any azimuthal dependence. The main-shock (Mw, 6.3) and the two largest aftershocks (Mw, 5.8, 5.3) show, however, a clear azimuthal dependence that indicates significant directivity effect. The discrepancy of the radiated spectral energy and the change in the corner frequencies introduced by directivity effects show that such an effect is significant at high frequency (from 1 to 25 Hz). Our data suggest that the amplitudes in the main-shock Fourier spectrum at directive sites are around a factor of 2.5 higher with respect to anti-directive sites.

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Section: Do Source Radiation Patterns Explain the Observed Azimuthal mentioning

confidence: 99%

High-frequency directivity effects: evidence from analysis of the Les Saintes records

et al. 2014

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“…However, in the context of Green’s function method for the simulation of earthquakes, a stress drop ratio (between the small event and the large one) greater than one is usually needed to accurately predict ground motion (e.g. Courboulex et al 2010).…”

Section: Introductionmentioning

confidence: 99%

New moment magnitude scale, evidence of stress drop magnitude scaling and stochastic ground motion model for the French West Indies

Drouet

Bouin

Cotton

2011

Geophysical Journal International

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International audienceIn this study we analyse records from the 'Les Saintes' seismic sequence following the Mw= 6.3 earthquake of 2004 November 11, which occurred close to Guadeloupe (French West Indies). 485 earthquakes with magnitudes from 2 to 6, recorded at distances between 5 and 150 km are used. S-waves Fourier spectra are analysed to simultaneously determine source, path and site terms. The results show that the duration magnitude routinely estimated for the events that occurred in the region underestimate moment magnitude by 0.5 magnitude units over the whole magnitude range. From the inverted seismic moments and corner frequencies, we compute Brune's stress drops. We show that stress drops increase with increasing magnitude. The same pattern is observed on apparent stresses (i.e. the seismic energy-to-moment ratio). However, the rate of increase diminishes at high magnitudes, which is consistent with a constant stress drop model for large events. Using the results of the inversions, we perform ground motion simulations for the entire data set using the SMSIM stochastic simulation tool. The results show that a good fit (σ= 0.25) with observed data is achieved when the source is properly described by its moment magnitude and stress drop, and when site effects are taken into account. Although the magnitude-dependent stress drop model is giving better results than the constant stress drop model, the interevent variability remains high, which could suggest that stress drop depends on other parameters such as the depth of the hypocentre. In any case, the overall variability is of the same order of magnitude as usually observed in empirical ground motion prediction equations

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“…If this information can be delivered rapidly, it may be used to evaluate and focus assistance in the most concerned zones. On November 21, 2004, the occurrence of Les Saintes event, M w = 6.3 and thousands of aftershocks in few days (IPGP, 2004;Bertil et al, 2004;Beauducel et al, 2005a;Courboulex et al, 2010;Bazin et al, 2010) offered an exceptional new strong-motion database thanks to the french permanent accelerometric network (Pequegnat et al, 2008(Pequegnat et al, ) installed in 2002(Pequegnat et al, -2004. Combined with collected testimonies and official intensity estimations for largest events, this provided a unique opportunity to establish a first local ground motion model adapted to the observatory needs.…”

Section: Introductionmentioning

confidence: 99%

Empirical model for rapid macroseismic intensities prediction in Guadeloupe and Martinique

Beauducel

Bazin

Bengoubou-Valerius

et al. 2011

Comptes Rendus Geoscience

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We describe a simple model for prediction of macroseismic intensities adapted to Guadeloupe and Martinique (Lesser Antilles), based on a combination of peak ground acceleration (PGA) predictive equation and a forward relation between acceleration and intensity. The PGA predictive equation is built from a 3-parameter functional form constrained by measurements from permanent accelerometer stations, mostly associated with Les Saintes crustal earthquake (21/11/2004, M w = 6.3) and its many aftershocks. The forward intensity model is checked on a database of recent instrumental events of various origins with magnitudes 1.6 to 7.4, distances from 4 to 300 km, and observed intensities from I to VIII. Global sigma residual equals 0.8 in the MSK scale, suggesting a larger applicability range than the intermediate PGA predictive equation. The model is presently used by the French Lesser Antilles observatories to produce automatic reports for earthquakes potentially felt. Résumé Nous proposons un modèle simple de prédiction des intensités macrosismiques adapté à la Guadeloupe et à la Martinique (Petites Antilles) basé sur la combinaison d'une loi d'atténuation des accélérations horizontales maximales (PGA) et d'une relation directe entre accélération et intensité. Le modèle prédictif des PGA est contruit à partir d'une équation fonctionnelle à 3 paramètres contrainte par des données provenant de stations accélérométriques permanentes principalement associées au séisme des Saintes (21/11/2004, M w = 6.3) et ses nombreuses répliques. Le modèle prédictif d'intensité est testé sur une base de données instrumentale de séismes récents, de magnitudes 1.6 à 7.4, distances 4 à 300 km et intensités observées entre I et VIII. Le résidu RMS final est de 0.8 sur l'échelle MSK, ce qui suggère un plus large domaine d'applicabilité que le modèle intermédiaire des PGA. Le modèle est actuellement utilisé par les observatoires des Antilles françaises pour produire des communiqués semi-automatiques lors de séismes susceptibles d'être ressentis. . Phone : +33 1 83 95 75 28. Fax : +33 1 83 95 77 17 Email address: beauducel@ipgp.fr (François Beauducel)deformed Caribbean plate with shallow crustal seismicity from 2 km up to 15-20 km in depth. Very shallow earthquakes occurring below/or very close to Guadeloupe archipelago islands can be felt sometimes with magnitude less than 2.0.

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Ground-Motion Simulations of the 2004 Mw 6.4 Les Saintes, Guadeloupe, Earthquake Using Ten Smaller Events

Cited by 13 publications

References 41 publications

High-frequency directivity effects: evidence from analysis of the Les Saintes records

High-frequency directivity effects: evidence from analysis of the Les Saintes records

New moment magnitude scale, evidence of stress drop magnitude scaling and stochastic ground motion model for the French West Indies

Empirical model for rapid macroseismic intensities prediction in Guadeloupe and Martinique

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