scholarly journals Crustal and upper mantle velocity structure in the vicinity of the eastern Tennessee seismic zone based upon radial P wave transfer functions

2015 ◽  
Vol 120 (1) ◽  
pp. 243-258 ◽  
Author(s):  
Jordan H. Graw ◽  
Christine A. Powell ◽  
Charles A. Langston
Keyword(s):  
Upper Mantle ◽  
Velocity Structure ◽  
Transfer Functions ◽  
P Wave ◽  
Seismic Zone ◽  
Mantle Velocity ◽  
Eastern Tennessee Seismic Zone

Upper Mantle velocity structure in the Hindukush region from travel time studies of deep earthquakes using a new analytical method

1969 ◽  
Vol 59 (5) ◽  
pp. 1949-1967
Author(s):  
K. L. Kaila ◽  
V. G. Krishna ◽  
Hari Narain
Keyword(s):  
Analytical Method ◽  
Upper Mantle ◽  
Velocity Structure ◽  
Focal Depth ◽  
P Wave ◽  
S Wave ◽  
Deep Earthquakes ◽  
Calibration Curves ◽  
Depth Determination ◽  
Mantle Velocity

abstract Upper Mantle velocity structure in the Hindukush region has been determined from the P- and S-wave travel times of 28 deep earthquakes making use of a new analytical method given by Kaila (1969). From a depth of 45 to 230 kms, the present analysis reveals a continuous linear increase of P-wave velocity from 8.21 to 8.52 km/sec. For S waves, however, the velocity increases linearly from 4.58 km/sec at a depth of 85 kms to 4.77 km/sec at 230 kms depth. Upper mantle velocities in the Hindukush region are found to be considerably higher in comparison to those for other regions of the Earth. Within the accuracy of the velocity determination from the present method, no inferences can be drawn regarding the existence or otherwise of the low-velocity channel in this region. Calibration curves for focal depth determination in the Hindukush region are also drawn. The accuracy of focal depth determination from these calibration curves is of the same order as that obtained in the focal depths determined by making use of pP, sS and other reflected phases.

Upper-mantle discontinuity from amplitude data of P′P′ and its precursors

1973 ◽  
Vol 63 (2) ◽  
pp. 587-597
Author(s):  
Ta-Liang Teng ◽  
James P. Tung
Keyword(s):  
Upper Mantle ◽  
Body Waves ◽  
P Wave ◽  
Specific Reference ◽  
Amplitude Data ◽  
Surface Displacements ◽  
Short Period ◽  
Mantle Velocity ◽  
Mantle Discontinuity ◽  
Upper Mantle Discontinuity

abstract Recent observations of P′P′ and its precursors, identified as reflections from within the Earth's upper mantle, are used to examine the structure of the uppermantle discontinuities with specific reference to the density, the S velocity, and the Q variations. The Haskell-Thomson matrix method is used to generate the complex reflection spectrum, which is then Fourier synthesized for a variety of upper-mantle velocity-density and Q models. Surface displacements are obtained for the appropriate recording instrument, permitting a direct comparison with the actual seismograms. If the identifications of the P′P′ precursors are correct, our proposed method yields the following: (1) a structure of Gutenberg-Bullen A type is not likely to produce observable P′P′ upper-mantle reflections, (2) in order that a P′P′ upper-mantle reflection is strong enough to be observed, first-order density and S-velocity discontinuities together with a P-wave discontinuity are needed at a depth of about 650 km, and (3) corresponding to a given uppermantle velocity-density model, an estimate can be made of the Q in the upper mantle for short-period seismic body waves.

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