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Within-station variability in kappa; evidence of directionality effects

Chunyang Ji, Ashly Cabas, Fabrice Cotton, Marco Pilz and Dino Bindi
Within-station variability in kappa; evidence of directionality effects
Bulletin of the Seismological Society of America (June 2020) 110 (3): 1247-1259

Abstract

One of the most commonly used parameters to describe seismic attenuation is the high-frequency spectral decay parameter Kappa (kappa (sub r) ), yet the physics behind it remain little understood. A better understanding of potential factors that lead to large scatter in estimated values of kappa (sub r) constitutes a critical need for ground-motion modeling and seismic hazard assessment at large. Most research efforts to date have focused on studying the site-to-site and model-to-model variability of kappa , but the uncertainties in individual kappa (sub r) estimations associated with different events at a selected site (which we refer to as the within-station variability of kappa (sub r) ) remain uncharacterized. As a direct corollary, obtaining robust estimates of the site-specific component kappa (sub 0) , and their corresponding interpretation become a challenge. To understand the sources of the variability observed in kappa (sub r) (and kappa (sub 0) ) at a single site, we select 10 Japanese Kiban-Kyoshin network (KiK-net) downhole arrays and investigate the systematic contributions from ground-motion directionality. We observe that kappa (sub r) estimated from a single horizontal component is orientation dependent. In addition, the influence of ground-motion directionality is a function of local site conditions. We propose an orientation-independent kappa (sub r) -value, which is not affected either by ground-motion directionality or by the events' azimuths. In addition, we find that focal depth of events used in kappa (sub r) calculations affects the estimation of the regional attenuation component kappa (sub R) , which, in turn, influences the within-station variability in the kappa (sub 0) model.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 110
Serial Issue: 3
Title: Within-station variability in kappa; evidence of directionality effects
Affiliation: North Carolina State University, Department of Civil, Construction, and Environmental Engineering, Raleigh, NC, United States
Pages: 1247-1259
Published: 202006
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 55
Accession Number: 2021-004779
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sketch maps
N36°00'00" - N38°00'00", E138°00'00" - E142°00'00"
Secondary Affiliation: German Research Centre for Geosciences, DEU, Germany
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2021, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 202102
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