Regional Variations of P-Wave Velocity in the Upper Mantle Beneath North America

2013 ◽  
pp. 242-246 ◽  
Author(s):  
Eugene Herrin
Keyword(s):  
North America ◽  
Wave Velocity ◽  
Upper Mantle ◽  
P Wave ◽  
Regional Variations ◽  
P Wave Velocity

Upper mantle structure in the Basin and Range province, western North America, from the apparent velocities of S waves

1969 ◽  
Vol 59 (4) ◽  
pp. 1653-1665
Author(s):  
Robert L. Kovach ◽  
Russell Robinson
Keyword(s):  
North America ◽  
Wave Velocity ◽  
Velocity Gradient ◽  
Upper Mantle ◽  
Shear Velocity ◽  
Basin And Range ◽  
P Wave ◽  
Western North America ◽  
Basin And Range Province ◽  
S Waves

Abstract The variation of shear velocity with depth in the upper mantle for the Basin and Range province of western North America has been studied with direct measurements of dT/dΔ for S waves in the distance range 14° < Δ < 40°. Three orthogonal components of digital data were used and onset times were determined using the product of the horizontal radial and vertical components of motion and particle motion diagrams. A linear LRSM array in Arizona was used for the measurement of dT/dΔ. An S-wave velocity distribution is derived, compatible with P-wave velocity models for the same region. The derived model consists of a thin lid zone of shear velocity 4.5 km/sec overlying a low-velocity zone and a change in velocity gradient at a depth of 160 km. Two regions of high-velocity gradient are located at depths beginning at 360 km and 620 km.

An amplitude constrained P-wave velocity profile for the upper mantle beneath the Eastern United States

1979 ◽  
Vol 69 (6) ◽  
pp. 1733-1744
Author(s):  
George A. McMechan
Keyword(s):  
United States ◽  
Velocity Profile ◽  
Wave Velocity ◽  
Upper Mantle ◽  
Epicentral Distance ◽  
P Wave ◽  
Eastern United States ◽  
Lateral Velocity ◽  
The North ◽  
P Wave Velocity

abstract A P-wave velocity profile for the upper mantle at depths between 200 and 800 km beneath Eastern United States has been constructed from a combination of data from natural and artificial sources. Data for this part of the upper mantle are scarce, particularly beyond 20° epicentral distance, because of the sparse distribution of relevant sources and stations. Nevertheless, this study is the first to use amplitude constraints in a model determination for this region, and the model that has been chosen can account for the main observed amplitude features as well as travel times. The resulting velocity profile is similar to those previously determined for the regions to the north and west, but has a broadening of velocity transitions relative to those in the western United States. Evidence is found for the existence of lateral velocity inhomogeneity within the mantle.

Calculations of upper-mantle P-wave velocity anisotropies

1979 ◽  
Vol 56 (1-2) ◽  
pp. 49
Author(s):  
Jean-Claude C. Mercier ◽  
Neville L. Carter
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
P Wave ◽  
P Wave Velocity
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