<?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>Shunroku Yamamoto</dc:contributor>
  <dc:contributor>William L. Ellsworth</dc:contributor>
  <dc:creator>Shunta Noda</dc:creator>
  <dc:date>2016</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;We propose a simple approach to measure earthquake magnitude&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;using the time difference (&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;&lt;span&gt;op&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;) between the body‐wave onset and the arrival time of the peak high‐frequency amplitude in an accelerogram. Measured in this manner, we find that&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;&lt;span&gt;w&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;is proportional to 2log&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;&lt;span&gt;op&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;for earthquakes 5&amp;le;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;&lt;span&gt;w&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;le;7, which is the theoretical proportionality if&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;&lt;span&gt;op&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;is proportional to source dimension and stress drop is scale invariant. Using high‐frequency (&amp;gt;2&amp;thinsp;&amp;thinsp;Hz) data, the root mean square (rms) residual between&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;&lt;span&gt;w&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;and&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;&lt;span&gt;&lt;i&gt;T&lt;/i&gt;&lt;span&gt;op&lt;/span&gt;&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;(&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;estimated from&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;&lt;span&gt;op&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;) is approximately 0.5 magnitude units. The rms residuals of the high‐frequency data in passbands between 2 and 16&amp;nbsp;Hz are uniformly smaller than those obtained from the lower‐frequency data.&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;span&gt;op&lt;/span&gt;&lt;span&gt;&amp;nbsp;depends weakly on epicentral distance, and this dependence can be ignored for distances &amp;lt;200&amp;thinsp;&amp;thinsp;km. Retrospective application of this algorithm to the 2011 Tohoku earthquake produces a final magnitude estimate of&amp;nbsp;&lt;/span&gt;&lt;i&gt;M&lt;/i&gt;&lt;span&gt;&amp;nbsp;9.0 at 120&amp;nbsp;s after the origin time. We conclude that&amp;nbsp;&lt;/span&gt;&lt;i&gt;T&lt;/i&gt;&lt;sub&gt;&lt;span&gt;op&lt;/span&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;of high‐frequency (&amp;gt;2&amp;thinsp;&amp;thinsp;Hz) accelerograms has value in the context of earthquake early warning for extremely large events.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/0120150108</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>Rapid estimation of earthquake magnitude from the arrival time of the peak high-frequency amplitude</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>