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<p>a computer processes receiver data to produce a 3D image, although CT scans use <a href="page.php?w=attenuation">attenuation</a> instead of travel-time difference. Seismic tomography has to deal with the analysis of curved ray paths which are reflected and refracted within the Earth, and potential uncertainty in the location of the earthquake <a href="page.php?w=hypocenter">hypocenter</a>. CT scans use linear x-rays and a known source.</p>

<p><big> History </big></p>
<p>In the early 20th century, <a href="page.php?w=Seismology">seismologists</a> first</p><p>
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