<?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>M.J.S. Johnston</dc:contributor>
  <dc:contributor>G. Glassmoyer</dc:contributor>
  <dc:creator>R. D. Borcherdt</dc:creator>
  <dc:date>1989</dc:date>
  <dc:description>&lt;p&gt;Volumetric strain meters (Sacks-Evertson design) are installed at 15 sites along the San Andreas fault system, to monitor long-term strain changes for earthquake prediction. Deployment of portable broadband, high-resolution digital recorders (GEOS) at several of the sites extends the detection band for volumetric strain to periods shorter than 5 × 10&lt;sup&gt;−2&lt;/sup&gt;&amp;nbsp;sec and permits the simultaneous observation of seismic radiation fields using conventional short-period pendulum seismometers. Simultaneous observations establish that the strain detection bandwidth extends from periods greater than 10&lt;sup&gt;7&lt;/sup&gt;&amp;nbsp;seconds to periods near 5 × 10&lt;sup&gt;−2&lt;/sup&gt;&amp;nbsp;sec with a dynamic range exceeding 140 dB. Measurements of earth-strain noise for the period band, 10&lt;sup&gt;7&lt;/sup&gt;&amp;nbsp;to 10&lt;sup&gt;−2&lt;/sup&gt;&amp;nbsp;sec, show that ground noise, not instrument noise, currently limits the measurement of strain over a bandwidth of more than eight orders of magnitude in period. Comparison of the short-period portion of earth-strain, noise spectra (20 to 5 × 10&lt;sup&gt;−2&lt;/sup&gt;&amp;nbsp;sec) with average spectra determined from pendulum seismometers, suggest that observed noise is predominantly dilatational energy. Recordings of local and regional earthquakes indicate that dilatometers respond to&amp;nbsp;&lt;i&gt;P&lt;/i&gt;&amp;nbsp;energy but not direct shear energy and that straingrams can be used to resolve superimposed reflected&amp;nbsp;&lt;i&gt;P&lt;/i&gt;&amp;nbsp;and&amp;nbsp;&lt;i&gt;S&lt;/i&gt;&amp;nbsp;waves for inference of wave characteristics not permitted by either sensor alone. Simultaneous measurements of incident&amp;nbsp;&lt;i&gt;P&lt;/i&gt;- and&amp;nbsp;&lt;i&gt;S&lt;/i&gt;-wave amplitudes are used to introduce a technique for single-station estimates of wave field inhomogeneity, free-surface reflection coefficients and local material&amp;nbsp;&lt;i&gt;P&lt;/i&gt;&amp;nbsp;velocity. Estimates of these parameters derived for the North Palm Springs earthquake (&lt;i&gt;M&lt;sub&gt;w&lt;/sub&gt;&lt;/i&gt;&amp;nbsp;5.9) respectively for an incident&amp;nbsp;&lt;i&gt;P&lt;/i&gt;&amp;nbsp;wave of 29° are −85°, 1.71, 2.9 km/sec, and for an incident&amp;nbsp;&lt;i&gt;S&lt;/i&gt;&amp;nbsp;wave of 17° are 79°, 0.85, 2.9 km/sec. The empirical estimates of reflection coefficients are consistent with model estimates derived using an anelastic half-space model with incident inhomogeneous wave fields.&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/BSSA0790041006</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>On the use of volumetric strain meters to infer additional characteristics of short-period seismic radiation</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>