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Investigation of Attenuation and Blockage of Lg in the Vicinity of the Kyrgyz Array,

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Synthetic seismograms and ray paths obtained by 3-D dynamic ray tracing are compared with regional seismograms from the KNET array in the Republic of Kyrgyzstan, in the former Soviet Union. Variations in regional waveforms recorded by the KNET array in the Republic of Kyrgyzstan are compared with predicted variations in the paths of multiple SmS waves comprising the Lg phase using the database of Moho topography by Fielding et al. 1993. Ray diagrams predict strong regional variations Lg efficiency in Kyrgyz area. The strongest variations in observed Lg amplitudes and predicted Lg paths are associated with strong gradients in Moho topography along the Hindu Kush and Pamir mountain ranges. Lg is nearly extinguished for paths from shallow events to the southwest of the Kyrgyz array, which traverse regions of strong Moho gradient Detailed variations of waveforms across the Kyrgyz array are consistent with Lg efficiency being proportional to the length and number of times SmS ray paths traverse regions of strong Moho gradient Synthetic seismograms predict that crustal thickness variations will either compress or stretch the Lg coda compared to that predicted in a crust of uniform thickness.

Subject Categories:

  • Government and Political Science
  • Geology, Geochemistry and Mineralogy
  • Seismology
  • Seismic Detection and Detectors
  • Nuclear Weapons

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