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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:creator>Art McGarr</dc:creator>
  <dc:date>1991</dc:date>
  <dc:description>&lt;div class=" metis-abstract"&gt;&lt;div class="article-section__content en main"&gt;&lt;p&gt;To estimate the seismic hazard to underground facilities or operations in the environs of a mining-induced tremor or a natural earthquake, it is useful to be able to relate locally recorded seismic waveforms to peak ground velocity and slip at the causative fault. For this purpose, far-field&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;wave pulses are analyzed to define the faulting slip&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;D&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and near-fault peak ground velocity&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;D&lt;/i&gt;/2 that give rise to the most significant ground motion. This most intense region of faulting, an assumed circular asperity, has radius&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;within a broader source zone of radius&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;, which is traditionally calculated from the corner frequency of the&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;wave spectrum. In developing relationships between peak far-field velocity v and peak acceleration a, and the source processes of the asperity,&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;D&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;D&lt;/i&gt;, as well as its radius&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;, the key model assumption is that&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;=&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;k&lt;/i&gt;β/ω, where ω is the angular frequency of the sinusoidal velocity pulse of maximum amplitude, β is the sheaf wave speed, and&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;k&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is a constant. Observations in deep-level gold mines of fault slip and slip velocity as well as laboratory observations of slip rate as a function of stress drop for stick-slip failure support a choice of about&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;k&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 2.34, the value commonly used for estimating&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;using the Brune model. In particular, observations of fault slip up to 410 mm for mining-induced tremors in the moment magnitude range 4–5 are consistent with&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;D&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 8.1&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;v/β, where&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;R&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is hypocentral distance. Moreover, estimates based on underground damage of near-fault ground velocities ranging up to 3.5 m/s are in accord with&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;D&lt;/i&gt;/2 = 1.28(β/μ)&lt;sub&gt;ρ&lt;/sub&gt;&lt;i&gt;R&lt;/i&gt;a, where μ is the modulus of rigidity and ρ is the density. Alternatively, the average slip velocity 〈&lt;i&gt;D&lt;/i&gt;〉 can be expressed in terms of the stress drop Δσ&lt;sub&gt;&lt;i&gt;a&lt;/i&gt;&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;of the asperity as 〈&lt;i&gt;D&lt;/i&gt;〉 = 0.51 β Δσ&lt;sub&gt;&lt;i&gt;a&lt;/i&gt;&lt;/sub&gt;/μ, and the agreement of this relationship with measurements made during stick-slip failure in the laboratory is good. To the extent that seismic slip exterior to the asperity is a consequence of preevent suppression of slip due to the asperity, the broader-scale(&lt;i&gt;r&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;) slip can be related to that of the asperity. Just as the asperity radius&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;can be estimated from&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= 2.34 βv/a, an alternative estimate for&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;is given by&lt;span&gt;&amp;nbsp;&lt;/span&gt;&lt;i&gt;r&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;&lt;span&gt;&amp;nbsp;&lt;/span&gt;= ρ&lt;i&gt;R&lt;/i&gt;a&lt;i&gt;M&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt;/[75.8ρμ(&lt;i&gt;R&lt;/i&gt;v)&lt;sup&gt;2&lt;/sup&gt;], the results of which are generally in good agreement with estimates based on the spectral corner frequency method.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1029/91JB01379</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Geophysical Union</dc:publisher>
  <dc:title>Observations constraining near-source ground motion estimated from locally recorded seismograms</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>