<?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>S.-B. Yu</dc:contributor>
  <dc:creator>J.C. Savage</dc:creator>
  <dc:date>2007</dc:date>
  <dc:description>&lt;div id="16137073" class="article-section-wrapper js-article-section js-content-section  " data-section-parent-id="0"&gt;&lt;p&gt;We treat both the number of earthquakes and the deformation following a mainshock as the superposition of a steady background accumulation and the postearthquake process. The preseismic displacement and seismicity rates&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;sub&gt;u&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;sub&gt;E&lt;/sub&gt;&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;are used as estimates of the background rates. Let&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;t&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;be the time after the mainshock,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) +&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;the postseismic displacement less the background accumulation&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;sub&gt;u&lt;/sub&gt;t&lt;/i&gt;, and Δ&lt;i&gt;N&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) the observed cumulative number of postseismic earthquakes less the background accumulation&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;sub&gt;E&lt;/sub&gt;t&lt;/i&gt;. For the first 160 days (duration limited by the occurrence of another nearby earthquake) following the Chengkung (&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;6.5, 10 December 2003, eastern Taiwan) and the first 560 days following the Parkfield (&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;6.0, 28 September 2004, central California) earthquakes&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) +&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is a linear function of Δ&lt;i&gt;N&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;). The aftershock accumulation Δ&lt;i&gt;N&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) for both earthquakes is described by the modified Omori Law&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;d&lt;/i&gt;Δ&lt;i&gt;N&lt;/i&gt;/&lt;i&gt;dt&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;∝ (1 +&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;t&lt;/i&gt;/&lt;i&gt;τ&lt;/i&gt;)&lt;sup&gt;−&lt;i&gt;p&lt;/i&gt;&lt;/sup&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;with&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;p&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 0.96 and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;τ&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 0.03 days. Although the Chengkung earthquake involved sinistral, reverse slip on a moderately dipping fault and the Parkfield earthquake right-lateral slip on a near-vertical fault, the earthquakes share an unusual feature: both occurred on faults exhibiting interseismic fault creep at the surface. The source of the observed postseismic deformation appears to be afterslip on the coseismic rupture. The linear relation between&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) +&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;N&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) suggests that this afterslip also generates the aftershocks. The linear relation between&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) +&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;u&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and Δ&lt;i&gt;N&lt;/i&gt;(&lt;i&gt;t&lt;/i&gt;) obtains after neither the 1999&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;7.1 Hector Mine (southern California) nor the 1999&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;7.6 Chi-Chi (central Taiwan) earthquakes, neither of which occurred on fault segments exhibiting fault creep.&lt;/p&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/0120070069</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>Postearthquake relaxation and aftershock accumulation linearly related after the 2003 M 6.5 Chengkung, Taiwan, and the 2004 M 6.0 Parkfield, California, earthquakes</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>