Caracas, Venezuela, Site Effect Determination with Microtremors

Duval, Anne-Marie; Vidal, Sylvain; Meneroud, J; Singer, André; Santis, F. De; Ramos, César; Romero, Gloria; Rodriguez, Renato; Pernia, A.; Reyes, Nicolás; Griman, C.

doi:10.1007/978-3-0348-8177-7_14

Cited by 20 publications

(12 citation statements)

References 3 publications

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“…Among several methods (e.g., site-to-reference spectral ratios, horizontal-tovertical spectral ratios [HVNSRs], array-data analysis), many authors use ambient noise vibrations (microtremors, hereinafter) to retrieve these parameters. In particular, following Nakamura (1989), the HVNSR of microtremors has been widely used to determine the resonance frequency of a site and has been applied successfully in urban environments (Duval et al, 2001;Lebrun et al, 2001;Panou et al, 2005). There are many reasons why use of this technique spread very rapidly: (1) it can be applied in regions with low seismicity rates, (2) a short time of acquisition is required in the field, and (3) low computational time and minimal computing resources are needed to analyze data.…”

Section: Introductionmentioning

confidence: 99%

Microtremor Measurements in the City of Palermo, Italy: Analysis of the Correlation between Local Geology and Damage

Cara¹,

Cultrera²,

Azzara³

et al. 2008

Bulletin of the Seismological Society of America

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This study presents the results of 90 seismic ambient noise measurements in Palermo, the main city of Sicily (Italy). The dataset has been processed using the horizontal-to-vertical spectral ratio (HVNSR) technique and interpreted in terms of local geology, which is characterized by the presence of alluvial sediments of two riverbeds masked by urbanization since the seventeenth century. HVNSRs show significant variations in the study area: when the transition stiff to soft is crossed, a typical spectral peak appears in the HVNSRs, mostly in the frequency band 1-2 Hz, and exceeding a factor of 3 in amplitude. Using available information on subsurface geological structure, we compute theoretical 1D and 2D transfer functions. The resonance frequencies of soft soils obtained by HVNSR are well reproduced by the fundamental frequencies from numerical modeling.The distribution of frequency peaks of HVNSR and their amplitudes are also compared with the local damage caused by historical earthquakes. Previous studies demonstrated that damage variations in Palermo were controlled more by near-surface geology than building vulnerability. A uniform vulnerability is an ideal condition to test statistical methods and their capability in seeking correlation between HVNSR and potential damage due to local geological conditions. We apply two well-established multivariate statistical methodologies (factor analysis and canonical correlation) to the HVNSR dataset and macroseismic data (damage grades of the European macroseismic scale). Through these analyses we quantify the significance of the correlation between the HVNSR peak in the low-medium frequency range (0.5-3 Hz) and the occurrence of the highest damage grades. This approach allows us (1) to estimate the threshold value in the resulting linear combination of the HVNSR amplitudes, which separates zones of light damage from zones of significant damage, and therefore (2) to improve the spatial definition of potentially high hazard zones through a denser grid of microtremor measurements.

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Section: Introductionmentioning

confidence: 99%

Microtremor Measurements in the City of Palermo, Italy: Analysis of the Correlation between Local Geology and Damage

Cara¹,

Cultrera²,

Azzara³

et al. 2008

Bulletin of the Seismological Society of America

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“…Here we analyze the wave propagation in a simplified model of the Caracas basin, as described by Duval et al [2001]. Although we retain only the separation between sediments and bedrock, the shape preserves the geometrical complexities of basins.…”

Section: A 2d Geological Basin Geometrymentioning

confidence: 99%

Interaction between surface waves and absorbing boundaries for wave propagation in geological basins: 2D numerical simulations

Festa

2005

Geophysical Research Letters

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[1] Surface waves control the peak of the seismic records at regional and teleseismic distances. In complex structures, such as basins, their amplitude is produced by the interference between the topography and the wedges of the model. Therefore, they represent a challenging target for numerical simulations. When modelling low frequencies in thin media, such as basins and waveguides, some instabilities arise from the interaction between propagating evanescent waves and the artificial layer, required to avoid spurious reflection to be sent back into the elastic volume. Here we propose to generalize the absorbing boundary conditions, by adding a cut-off frequency and an overdamping. The efficiency is demonstrated through a comparison with analytical solutions. Finally an analysis is performed by adopting a complex basin geometry, where we show that the pollution of classical absorbing conditions becomes significant near the edges of the model. Citation: Festa, G., E. Delavaud, and J.-P. Vilotte (2005), Interaction between surface waves and absorbing boundaries for wave propagation in geological basins: 2D numerical simulations,

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“…The HVSR method has been used extensively to evaluate site effects, seismic microzonation, and basin structure (e.g., Fäh et al, 1997;Guéguen et al, 2000;Alfaro et al, 2001;Duval et al, 2001;Navarro et al, 2001;Panou et al, 2005;Chatelain, Guillier, Parvez, 2008;Bensalem et al, 2010). In such studies, one assumes a 1D soil column.…”

Section: Introductionmentioning

confidence: 98%

Basement Mapping with Single-Station and Array Ambient Vibration Data: Delineating Faults under Boumerdes City, Algeria

Hellel¹,

Oubaiche²,

Chatelain³

et al. 2012

Seismological Research Letters

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Caracas, Venezuela, Site Effect Determination with Microtremors

Cited by 20 publications

References 3 publications

Microtremor Measurements in the City of Palermo, Italy: Analysis of the Correlation between Local Geology and Damage

Microtremor Measurements in the City of Palermo, Italy: Analysis of the Correlation between Local Geology and Damage

Interaction between surface waves and absorbing boundaries for wave propagation in geological basins: 2D numerical simulations

Basement Mapping with Single-Station and Array Ambient Vibration Data: Delineating Faults under Boumerdes City, Algeria

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