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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Eric M. Thompson</dc:contributor>
  <dc:contributor>Heloise Cadet</dc:contributor>
  <dc:creator>David M. Boore</dc:creator>
  <dc:date>2011</dc:date>
  <dc:description>Using velocity profiles from sites in Japan, California, Turkey, and Europe, we find that the time-averaged shear-wave velocity to 30 m (&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt;), used as a proxy for site amplification in recent ground-motion prediction equations (GMPEs) and building codes, is strongly correlated with average velocities to depths less than 30 m (&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;Sz&lt;/i&gt;&lt;/sub&gt;, with &lt;i&gt;z&lt;/i&gt; being the averaging depth). The correlations for sites in Japan (corresponding to the KiK-net network) show that &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;Sz&lt;/i&gt;&lt;/sub&gt; is systematically larger for a given &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;Sz&lt;/i&gt;&lt;/sub&gt; than for profiles from the other regions. The difference largely results from the placement of the KiK-net station locations on rock and rocklike sites, whereas stations in the other regions are generally placed in urban areas underlain by sediments. Using the KiK-net velocity profiles, we provide equations relating &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; to &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;Sz&lt;/i&gt;&lt;/sub&gt; for &lt;i&gt;z&lt;/i&gt; ranging from 5 to 29 m in 1-m increments. These equations (and those for California velocity profiles given in Boore, 2004b) can be used to estimate &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; from &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;Sz&lt;/i&gt;&lt;/sub&gt; for sites in which velocity profiles do not extend to 30 m. The scatter of the residuals decreases with depth, but, even for an averaging depth of 5 m, a variation in log&lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; of ±1 standard deviation maps into less than a 20% uncertainty in ground motions given by recent GMPEs at short periods. The sensitivity of the ground motions to &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; uncertainty is considerably larger at long periods (but is less than a factor of 1.2 for averaging depths greater than about 20 m). We also find that &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; is correlated with &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;Sz&lt;/i&gt;&lt;/sub&gt; for &lt;i&gt;z&lt;/i&gt; as great as 400 m for sites of the KiK-net network, providing some justification for using &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; as a site-response variable for predicting ground motions at periods for which the wavelengths far exceed 30 m.</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/0120110071</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>Regional correlations of V&lt;sub&gt;&lt;i&gt;S&lt;/i&gt;30&lt;/sub&gt; averaged over depths less than and greater than 30 meters</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>