Observations of explosion generated PcP spectra at near-normal incidence |
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| Institution: | 1. J. Mack Robinson College of Business, Georgia State University, 35 Broad Street, Suite 1234, Atlanta, GA 30303, USA;2. University of Mannheim, L9, 1-2. 68161 Mannheim, Germany;3. University of St. Gallen, Swiss Institute of Banking and Finance, Unterer Graben 21, 9000 St. Gallen, Switzerland |
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| Abstract: | Short period recordings of PcP at the SRO station ANTO have been observed at epicentral distance of 13.5° from presumed underground explosions in western Kazahk, USSR. The core reflections are narrow band (0.6 to 2.4 Hz), short duration (3 sec) signals. Comparison of these near normally incident reflections to P waveforms observed at greater distances reveals that the PcP spectra are peaked with respect to the more representative P-wave spectra. The 1.2 Hz spectral peak is also observed for PcP waves recorded at 50 degrees. Corrections for frequency independent mantle Q attnuation models only increase the high frequency deficiency of the PcP spectra at frequencies above 1.2 Hz. A plausible explanation calls for finer structural features of core-mantle boundary (CMB) than hitherto suggested. The influence of small scale lateral heterogeneities, however, cannot be completely ruled out. (Mantle-core boundary, near normal PcP reflection.) |
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