<?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>John R. Filson</dc:contributor>
  <dc:contributor>Edward Cranswick</dc:contributor>
  <dc:contributor>Roger D. Borcherdt</dc:contributor>
  <dc:contributor>Ruben Amirbekian</dc:contributor>
  <dc:contributor>Vigen Aharonian</dc:contributor>
  <dc:contributor>Leon Hachverdian</dc:contributor>
  <dc:creator>Jim Mori</dc:creator>
  <dc:date>1994</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;The &lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt;- and &lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt;-wave arrivals from local earthquakes were studied using an array of 10 three-component instruments in and around a tunnel at Garni Observatory, Armenia. The array has a three-dimensional configuration with lateral dimensions of 300 to 500 m and a depth extent of 100 m. Estimates of the horizontal and vertical components of slowness for &lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt; and &lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt; wave fronts were used to determine the angles of approach and the propagation velocity. The results showed that the region around the array has low average velocities for both the &lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt; (1.43 km/sec) and &lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt; (0.61 km/sec) waves, so wave fronts approach the array at steep angles of incidence. Waveforms from one event show clear reflections from the free surface for both &lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt; and &lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt; waves. The timing of these reflections gives the velocity variation with depth within the array. We estimated a &lt;/span&gt;&lt;i&gt;P&lt;/i&gt;&lt;span&gt; velocity of 0.33 km/sec within a few meters of the surface, increasing to several kilometers per second for the deepest portion of the array. Local site variations can greatly complicate the high-frequency waveforms, even for tunnel stations in bedrock. The &lt;/span&gt;&lt;i&gt;S&lt;/i&gt;&lt;span&gt; waves exhibit stronger site dependent waveforms and time delays than do the &lt;/span&gt;&lt;i&gt;P &lt;/i&gt;&lt;span&gt;waves.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1785/BSSA0840041089</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Seismological Society of America</dc:publisher>
  <dc:title>Measurements of P and S wave fronts from the dense three-dimensional array at Garni, Armenia</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>