<?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:creator>W. H. Bakun</dc:creator>
  <dc:date>1999</dc:date>
  <dc:description>&lt;div id="135076994" class="article-section-wrapper js-article-section js-content-section  " data-section-parent-id="0"&gt;&lt;p&gt;Moment magnitude&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;strong&gt;M&lt;/strong&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;with objective confidence-level uncertainties are estimated for felt San Francisco Bay region earthquakes using Bakun and Went-worth's (1997) analysis strategy for seismic intensity observations. The frequency-magnitude distribution is well described for&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;strong&gt;M&lt;/strong&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;≧ 5.5 events since 1850 by a Gutenberg-Richter relation with a&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;b&lt;/i&gt;-value of 0.90. The seismic moment rate Σ&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;/yr since 1836 is 2.68 × 10&lt;sup&gt;18&lt;/sup&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;N-m/yr (95% confidence range = 1.29 × 10&lt;sup&gt;18&lt;/sup&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;N-m/yr to 4.07 × 10&lt;sup&gt;18&lt;/sup&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;N-m/yr); the seismic moment rate since 1850 is nearly the same. Σ&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;/yr in the 56 years before 1906 is about 10 times that in the 70 years after 1906. In contrast, Σ&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;/yr since 1977 is about equal that in the 56 years before 1906. 80% (1σ = 14%) of the plate-motion moment accumulation rate is available for release in earthquakes. The historical Σ&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;/yr and the portion of the plate-motion moment accumulation rate available for release in earthquakes are used in a seismic cycle model to estimate the rate of seismic activity in the twenty-first century. High and low rates of future seismic activity are both permissible given the range of possible seismic-cycle recurrence times&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and the uncertainties in the historical Σ&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and in the percentage of plate motion available for release in earthquakes. If the historical seismic moment rate is not greater than the estimated 2.68 × 10&lt;sup&gt;18&lt;/sup&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;N-m/yr and the percentage of the plate-motion moment accumulation available for release in earthquakes is not less than the estimated 80%, then for all&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;, the rate of seismic moment release from now until the next 1906-sized shock will be comparable to the rate from 1836 to 1905 when&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;strong&gt;M&lt;/strong&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;6 1/2 shocks occurred every 15 to 20 years.&lt;/p&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/BSSA0890030764</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>Seismic activity of the San Francisco Bay region</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>