A κ model for mainland France

John Douglas, Pierre Gehl, Luis Fabian Bonilla, Céline Ǵelis

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

An important parameter for the characterization of strong ground motion at high-frequencies (>1 Hz) is kappa, κ, which models a linear decay of the acceleration spectrum, a(f), in log-linear space (i.e. a(f) = A 0 exp(- π kf) for f>f E where f is frequency, f E is a low frequency limit and A 0 controls the amplitude of the spectrum). κ is a key input parameter in the stochastic method for the simulation of strong ground motion, which is particularly useful for areas with insufficient strong-motion data to enable the derivation of robust empirical ground motion prediction equations, such as mainland France. Numerous studies using strong-motion data from western North America (WNA) (an active tectonic region where surface rock is predominantly soft) and eastern North America (ENA) (a stable continental region where surface rock is predominantly very hard) have demonstrated that κ varies with region and surface geology, with WNA rock sites having a κ of about 0.04 s and ENA rock sites having a κ of about 0.006 s. Lower κs are one reason why high-frequency strong ground motions in stable regions are generally higher than in active regions for the same magnitude and distance. Few, if any, estimates of κs for French sites have been published. Therefore, the purpose of this study is to estimate κ using data recorded by the French national strong-motion network (RAP) for various sites in different regions of mainland France. For each record, a value of κ is estimated by following the procedure developed by Anderson and Hough (Bull Seismol Soc Am 74:1969-1993, 1984): this method is based on the analysis of the S-wave spectrum, which has to be performed manually, thus leading to some uncertainties. For the three French regions where most records are available (the Pyrenees, the Alps and the Côtes-d'Azur), a regional κ model is developed using weighted regression on the local geology (soil or rock) and source-to-site distance. It is found that the studied regions have a mean κ between the values found for WNA and ENA. For example, for the Alps region a κ value of 0.0254 s is found for rock sites, an estimate reasonably consistent with previous studies.

LanguageEnglish
Pages1303-1315
Number of pages13
JournalPure and Applied Geophysics
Volume167
Issue number11
Early online date20 Apr 2010
DOIs
Publication statusPublished - Nov 2010

Fingerprint

France
Rocks
rocks
ground motion
strong motion
Geology
rock
geology
estimates
Tectonics
S waves
wave spectrum
regression analysis
tectonics
soils
derivation
Soils
low frequencies
North America
S-wave

Keywords

  • France
  • high-frequency decay
  • Kappa
  • near-surface attenuation
  • RAP
  • strong-motion data

Cite this

Douglas, J., Gehl, P., Bonilla, L. F., & Ǵelis, C. (2010). A κ model for mainland France. Pure and Applied Geophysics, 167(11), 1303-1315. https://doi.org/10.1007/s00024-010-0146-5
Douglas, John ; Gehl, Pierre ; Bonilla, Luis Fabian ; Ǵelis, Céline. / A κ model for mainland France. In: Pure and Applied Geophysics. 2010 ; Vol. 167, No. 11. pp. 1303-1315.
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Douglas, J, Gehl, P, Bonilla, LF & Ǵelis, C 2010, 'A κ model for mainland France' Pure and Applied Geophysics, vol. 167, no. 11, pp. 1303-1315. https://doi.org/10.1007/s00024-010-0146-5

A κ model for mainland France. / Douglas, John; Gehl, Pierre; Bonilla, Luis Fabian; Ǵelis, Céline.

In: Pure and Applied Geophysics, Vol. 167, No. 11, 11.2010, p. 1303-1315.

Research output: Contribution to journalArticle

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