Seismological Research Letters; May/June 2009; v. 80; no. 3;
p. 440-445; DOI: 10.1785/gssrl.80.3.440
© 2009 Seismological Society of America
A Shear Wave Velocity Study Based on the Kik-net Borehole Data: A Short Note
Héloïse Cadet1,2,3 and
Anne-Marie Duval2
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INTRODUCTION
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Shear-wave velocity structure is a crucial factor for site characterization
and site effect assessment. There are several methods for estimating velocity
structure (intrusive or nondestructive, with active or passive sources). We
are not going to compare these different methods, but we will point out that
all methods have certain limits: penetration depth, resolution, and cost are
the main limiting factors. For instance, acquiring a complete and reliable
velocity profile from surface to hard bedrock is often difficult and
expensive. It is obvious that an alternative kind of parameter, instead of the
complete velocity profile, should be used for site characterization.
In order to classify a site, the average shear wave velocity of the first
30 m, VS30, is widely used in most building codes,
including the National Earthquake Hazards Reduction Program
(NEHRP 2000) and Eurocode 8
(1998). This measure was
originally chosen because it generally takes one day to realize a 30-m deep
geotechnical testing for most of the American sites (P. Y. Bard, personal
communication). So it was at first only a practical choice, but the
VS30 value is nowadays widely used and the number of
VS30 data is extremely high, so we cannot ignore this soil
parameter. However, many measurements of shear wave velocity do not reach 30
m, as Boore (2004) has noticed.
Thus, relationships between the different time-average velocity
VSz (for z = 5, 10, 20 30 m) parameters are of
great interest. This task has been done for California data
(Boore 2004) and will be
compared here with Japanese and some European data.
Following the 1995 Hyogo-ken Nanbu (Kobe) earthquake, the Japanese
government installed networks consisting of a large number of strong-motion
stations, including Kik-net (Kiban-Kyoshin), to improve the prevention of
future earthquake . . . [Full Text of this Article]
Institute of Engineering Seismology and
Earthquake Engineering
46 Georgikis Scholis Str.
P.O. Box 53
GR-55102 Finikas
Thessaloniki, Greece
heloise@itsak.gr
(H. C.)
Equipe de Recherche "Risque Sismique"
CETE
Méditerranée Laboratoire de Nice
56 bd Stalingrad
F-06359 Nice, France
anne-marie.duval@developpement-durable.gouv.fr
(A.-M. D.)
Copyright © 2009 by Seismological Society of America