Robustness of Kappa (k) Measurement in Low-to-Moderate Seismicity Areas: Insight from a Site-Specific Study in Provence, France
HOLLENDER ; BARD ; GELIS ; GUYONNET-BENAIZE ; HERNANDEZ ; KTENIDOU
Type de document
ARTICLE A COMITE DE LECTURE REPERTORIE DANS BDI (ACL)
Langue
anglais
Auteur
HOLLENDER ; BARD ; GELIS ; GUYONNET-BENAIZE ; HERNANDEZ ; KTENIDOU
Résumé / Abstract
Determination of the site component of º (º0) is important in the implementation of hosttotarget adjustments for estimation of seismic hazard at hardrock sites. Its evaluation through the classical approach of Anderson and Hough (1984), º0_AS, faces specific difficulties in lowtomoderate seismicity areas because the quantity and bandwidth of the usable data are generally limited. In such a context, measurements might have higher sensitivity to site amplification, frequencydependent attenuation, the earthquake source, and the instrumental equipment. Here, the ºDS (displacement spectrum) approach of Biasi and Smith (2001) is compared with the ºAS (acceleration spectrum) approach for three sites in an industrial area in Provence (southeastern France). A semiautomatic procedure is developed to measure individual values of ºr that reduce interoperator variability and provide the associated uncertainty. We show that this uncertainty is mainly dependent on the bandwidth used to determine ºr. A good agreement is found between º0_AS and º0_DS for the two hardrock sites, which yield <30 ms. This highlights the ºDS approach that is well adapted to lowmagnitude events recorded at rock sites, and the use of velocimeters in lowtomoderate seismicity areas. The comparisons between these approaches are also used to infer the reliability of º measurements by addressing their sensitivity to site amplification, frequencydependent attenuation, and the earthquake source. First, the impact of site amplification on º0 estimates is shown to be very important and strongly frequencydependent for stiffsoil sites, and nonnegligible for hardrock sites. Second, frequencydependent attenuation cannot be ruled out for º, as indicated by comparison with the literature quality factor (Q) for the Alps. Finally, a source component for ºAS is questionable from the comparison of ºr_AS evaluated for a cluster of events that shared the same path and site components.
Source
Bulletin of the Seismological Society of America, num. 5, pp.2272 - 2292 p.
Editeur
Seismological Society of America
