CHARACTERIZATION OF FRENCH ACCELEROMETRIC PERMANENT NETWORK STATIONS WITH SURFACE-WAVE BASED METHODS: IMPORTANCE OF JOINT USE OF ACTIVE AND PASSIVE METHODS, LOVE AND RAYLEIGH WAVES - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2017

CHARACTERIZATION OF FRENCH ACCELEROMETRIC PERMANENT NETWORK STATIONS WITH SURFACE-WAVE BASED METHODS: IMPORTANCE OF JOINT USE OF ACTIVE AND PASSIVE METHODS, LOVE AND RAYLEIGH WAVES

C Cornou
A Dechamp
  • Fonction : Auteur
  • PersonId : 1000761
F Renalier
  • Fonction : Auteur
S Thomassin
  • Fonction : Auteur
  • PersonId : 1000762
P.-y Bard

Résumé

Data provided by accelerometric networks are important for seismic hazard assessment. They are key to derive Ground Motion Prediction Equations (GMPEs). The correct use of accelerometric signal is also linked to the station site metadata that include reliable information about site class (VS30), velocity profiles, and other relevant information that can help to quantify the site effect associated to stations. In France, the permanent accelerometric network consists of about 150 stations. A recent project led to the characterization of around 30 stations, especially in South East of France. This characterization project was performed using surface-wave based methods that allow the derivation of velocity profiles from dispersion curves of Rayleigh and Love waves. We implemented both active acquisitions (Multichannel Analysis of Surface Waves) along lines from 50 to 100 m length and passive acquisitions (Ambient Vibration Array) using multiple circle arrays (apertures from 10 to 1000 m). The computation of dispersion curves, then their inversion in terms of shear wave velocity profiles (taking into account the non-uniqueness issue of such inversion) allowed the estimations of VS30 values and the designation of soil classes including the corresponding uncertainties. From a methodological point of view, this survey leads to the following recommendations: (1) Perform both active and passive measurements in order to derive dispersion curves for an adequate frequency range; (2) perform active acquisitions for both vertical (Rayleigh wave) and horizontal (Love wave) polarities, which reduces the risk of misattribution of modes and thus, mitigates errors when modeling velocity profiles. Even when logistical contexts are sometimes difficult, the use of surface-wave based methods are suitable for station site characterizations, even on rock sites (where the applicability of these methods was sometimes disputed). Typically, it is possible to achieve a complete survey for one station in one working day, by 5 to 6 motivated operators. Conversely, the processing is time consuming (one working week for one geophysicist) and the inversion procedure has to be supervised by an expert in surface wave methods.
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Dates et versions

hal-01461316 , version 1 (08-02-2017)

Identifiants

  • HAL Id : hal-01461316 , version 1

Citer

F. Hollender, C Cornou, A Dechamp, F Renalier, S Thomassin, et al.. CHARACTERIZATION OF FRENCH ACCELEROMETRIC PERMANENT NETWORK STATIONS WITH SURFACE-WAVE BASED METHODS: IMPORTANCE OF JOINT USE OF ACTIVE AND PASSIVE METHODS, LOVE AND RAYLEIGH WAVES. Sixteenth World Conference on Earthquake Engineering, Jan 2017, Santiago, Chile. pp.4939. ⟨hal-01461316⟩
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