Open AccessShear‐wave velocity structure for a spherically averaged earth
Author(s) -
Uhrhammer Robert
Publication year - 1979
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1979.tb04805.x
Subject(s) - geodesy , slowness , geology , wave velocity , shear velocity , elevation (ballistics) , shear (geology) , seismology , geometry , mathematics , meteorology , physics , petrology , turbulence
Summary. The shear‐wave velocity distribution in a spherically averaged Earth is estimated statistically from previously published short‐period S travel‐time measurements (Uhrhammer). An algorithm is defined for integral inversion techniques which allows estimation of the variance of the velocity distribution from the uncertainties in the S slowness model. Comparisons are made between the resulting S ‐velocity solution and other solutions in common use. There are significant differences (at the 95 per cent confidence level) between the 5‐velocity model determined here and the Jeffreys‐Bullen model over the depth ranges of 150–550 km and 2100–2350 km. The 95 per cent confidence level in the present velocity distribution ranges from ± 0.025 km/s at 625 km to ±0.32km/s at 2766 km and averages about ±0.063 or ±1 percent. Correlations between azimuthally dependent source and station adjustments (which were previously determined (Uhrhammer)) indicate widespread lateral inhomogeneities (up to 3.4 per cent) to depths of approximately 700 km. Up to three‐quarters of the source adjustments are due to lateral velocity variations in the source regions. Station adjustments for differential 5 minus P times are significantly correlated with elevation and crustal age, but not with station instrumental magnification.