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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:contributor>Bruce E. Jaffe</dc:contributor>
  <dc:contributor>Robert Kayen</dc:contributor>
  <dc:creator>Walter A. Barnhardt</dc:creator>
  <dc:date>1999</dc:date>
  <dc:description>&lt;p&gt;&lt;span class="EXLDetailsDisplayVal"&gt;&lt;span class="searchword"&gt;Ground&lt;/span&gt;-&lt;span class="searchword"&gt;penetrating&lt;/span&gt; &lt;span class="searchword"&gt;radar&lt;/span&gt; (GPR) and boreholes were used to investigate a &lt;span class="searchword"&gt;landslide&lt;/span&gt;-prone bluff at Sleeping Bear Dunes National Lakeshore on the northeastern coast of &lt;span class="searchword"&gt;Lake&lt;/span&gt; &lt;span class="searchword"&gt;Michigan&lt;/span&gt;. Based on borehole observations, sediment underlying the area is homogeneous, consisting of well-sorted, medium to coarse sand. GPR penetrated up to 20 m deep in these &lt;span class="searchword"&gt;sediments&lt;/span&gt;, revealing the late Quaternary stratigraphy in great detail. We define four units, or &lt;span class="searchword"&gt;radar&lt;/span&gt; facies, based on criteria similar to those used in seismic stratigraphy. Directly beneath a &lt;span class="searchword"&gt;landslide&lt;/span&gt; at Sleeping Bear Point (and nowhere else in this survey) is a deeply incised, channel-fill deposit that intersects the shoreline at a high angle. The buried channel is at least 10 m deep and 400 m wide, and it might be a subglacially carved feature of Pleistocene age. A prominent, planar unconformity marks the upper surface of the channel deposit, which is overlain by stratified beach and dune material. Several crosshole GPR surveys were performed in the vicinity of the landslide: 1) a constant offset profile (COP), 2) a multiple offset gather (MOG), and 3) a vertical radar profile (VRP). Tomographic analysis of these data determined the velocity structure of sandy sediment that underlie the failed bluff. Because GPR velocity is dependent on electrical properties, we use it as a proxy for geotechnical properties of the soils. Our working hypothesis is that the hidden channel may act as a conduit for pore water flow between upland regions and Lake Michigan, and thereby locally reduce soil strength and promote slope failure.&lt;/span&gt; &lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:language>en</dc:language>
  <dc:title>Evaluation of landslide hazards with ground-penetrating radar, Lake Michigan coast</dc:title>
  <dc:type>text</dc:type>
</oai_dc:dc>