| | AbstractThe most prominent
secondary phase observed in the records from the ultralong profile
``Quartz'' crossing northern Eurasia is the high-frequency long-range
(teleseismic) Pn. This phase, propagating with the
group velocity of about 8.1 to 8.2 km/sec to over 3000 km distances,
dominates the records within the frequency range above about 5 Hz.
Within this teleseismic Pn, we distinguish onsets of
several branches having higher apparent velocities between 8.5 and 8.6
km/sec. Using travel-time modeling techniques, we associate the
teleseismic Pn with whispering gallery modes traveling
within the top 160 km of the mantle. The long incoherent coda of this
phase results from scattering and from reverberations of seismic waves
within the crust. The contrast in frequency contents between the
teleseismic Pn and deeper refracted and reflected
phases is explained by the increase of inelastic attenuation within the
prominent low-velocity zone (LVZ) below the depth of about 150 km.Return to Table of
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