<?xml version='1.0' encoding='utf-8'?>
<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>James F. Gibbs</dc:contributor>
  <dc:contributor>William B. Joyner</dc:contributor>
  <dc:creator>David Boore</dc:creator>
  <dc:date>2021</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;A method discussed in&amp;nbsp;&lt;/span&gt;&lt;a class="link link-ref xref-bibr" data-modal-source-id="rf14"&gt;Gibbs, Boore,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;et&amp;nbsp;al.&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;(1994)&lt;/a&gt;&lt;span&gt;&amp;nbsp;was applied to surface‐source, downhole‐receiver recordings at 22 boreholes, in the San Francisco Bay area in central California and the San Fernando Valley of southern California, to determine the average damping ratio of shear waves over depth intervals ranging from about 10&amp;nbsp;m to as much as 245&amp;nbsp;m (at one site), with most maximum depths being between 35 and 90&amp;nbsp;m. The average damping values range from somewhat less than 1% to almost 8%, with little dependence on grain size for sites in sediments. Surprisingly, the average damping values for sites with average velocities greater than about&amp;nbsp;&lt;/span&gt;&lt;span class="inline-formula no-formula-id"&gt;&lt;span id="MathJax-Element-1-Frame" class="MathJax" data-mathml="&lt;math xmlns=&amp;quot;http://www.w3.org/1998/Math/MathML&amp;quot;&gt;&lt;mn xmlns=&amp;quot;&amp;quot;&gt;450&lt;/mn&gt;&lt;mtext xmlns=&amp;quot;&amp;quot;&gt;&amp;amp;#x2009;&amp;amp;#x2009;&lt;/mtext&gt;&lt;mi xmlns=&amp;quot;&amp;quot; mathvariant=&amp;quot;normal&amp;quot;&gt;m&lt;/mi&gt;&lt;mo xmlns=&amp;quot;&amp;quot;&gt;/&lt;/mo&gt;&lt;mi xmlns=&amp;quot;&amp;quot; mathvariant=&amp;quot;normal&amp;quot;&gt;s&lt;/mi&gt;&lt;/math&gt;"&gt;&lt;span id="MathJax-Span-1" class="math"&gt;&lt;span&gt;&lt;span id="MathJax-Span-2" class="mrow"&gt;&lt;span id="MathJax-Span-3" class="mn"&gt;450&lt;/span&gt;&lt;span id="MathJax-Span-4" class="mtext"&gt;  &lt;/span&gt;&lt;span id="MathJax-Span-5" class="mi"&gt;m&lt;/span&gt;&lt;span id="MathJax-Span-6" class="mo"&gt;/&lt;/span&gt;&lt;span id="MathJax-Span-7" class="mi"&gt;s&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;span class="MJX_Assistive_MathML"&gt;450  m/s&lt;/span&gt;&lt;/span&gt;⁠&lt;/span&gt;&lt;span&gt;, including, but not limited to rock sites, are generally larger than for sites with lower average velocities. The combined effect of the higher damping and shorter travel times through the rock columns, however, leads to an effective attenuation that is generally comparable or smaller than for soil sites.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/0120200225</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>Damping values derived from surface-source, downhole-receiver measurements at 22 sites in the San Francisco Bay Area of central California and the San Fernando Valley of southern California</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>