scholarly journals Upper mantle P wave velocity structure and transition zone thickness beneath the Arabian Shield

2003 ◽  
Vol 30 (10) ◽  
pp. n/a-n/a ◽  
Author(s):  
Margaret H. Benoit ◽  
Andrew A. Nyblade ◽  
John C. VanDecar ◽  
Harold Gurrola
Keyword(s):  
Transition Zone ◽  
Wave Velocity ◽  
Upper Mantle ◽  
Velocity Structure ◽  
P Wave ◽  
Arabian Shield ◽  
P Wave Velocity ◽  
P Wave Velocity Structure

Upper mantle P-wave velocity structure in the Japan region from travel-time studies of deep earthquakes using a new analytical method

1971 ◽  
Vol 61 (6) ◽  
pp. 1549-1570
Author(s):  
K. L. Kaila ◽  
V. G. Krishna ◽  
Hari Narain
Keyword(s):  
Wave Velocity ◽  
Calibration Curve ◽  
Velocity Gradient ◽  
Upper Mantle ◽  
Inflection Point ◽  
Velocity Structure ◽  
P Wave ◽  
Central Japan ◽  
P Wave Velocity ◽  
P Wave Velocity Structure

abstract The upper mantle P-wave velocity structure of the region of Japan has been studied in great detail from travel times of 107 earthquakes with focal depths varying from 40 to 600 km, using a new analytical method given by Kaila (1969). In southwestern Japan the P-wave velocity is found to be 7.88 km/sec at a 40-km depth, and it remains almost constant to a depth of 255 km. For northeastern Japan the velocity, determined as 7.88 km/sec at 40 km, increases linearly with moderate gradient to 8.14 km/sec at a 175-km depth. On the other hand, for central Japan the P-velocity is found to be 7.92 km/sec at a 40-km depth, and increases linearly with a high-velocity gradient to 8.33 km/sec at a depth of 180 km. Then, there is a slight decrease in the velocity gradient, but the velocity still increases linearly to 8.52 km/sec at a depth of 365 km. At this transition depth, there is a first-order velocity discontinuity—the velocity increasing from 8.52 to 9.10 km/sec. Below this depth, velocity again increases linearly from 9.10 to 9.99 km/sec at a depth of 600 km. Probable causes for these lateral-velocity inhomogeneities in the upper mantle of the Japan region are discussed. Graphs have been drawn to show the variation with depth of Δ*, the epicentral distance to the inflection point, (Δ2 − Δ1), ptrue = ∂T/∂Δ and ap = (T − pΔ) at the inflection point, the latter acting as a calibration curve for earthquake focal-depth determination in Japan. Using this calibration curve, focal depths are redetermined for all of the earthquakes under study for central Japan, and the same are compared with the values reported in the International Seismological Summaries.

P-Wave Residuals in Western Canada

1975 ◽  
Vol 12 (2) ◽  
pp. 174-181
Author(s):  
E. J. Roebroek ◽  
E. Nyland
Keyword(s):  
United States ◽  
Wave Velocity ◽  
Upper Mantle ◽  
Velocity Structure ◽  
The United States ◽  
P Wave ◽  
Western Canada ◽  
Lateral Variation ◽  
P Wave Velocity ◽  
P Wave Velocity Structure

A study of over 1500 P-wave phases which pass, for the most part, through the upper mantle beneath Western Canada, shows that there is no significant lateral variation in P-wave velocity structure beneath Western Canada, and that the Wiggins and Helmberger model for the Western regions of the United States does not fit the data for Western Canada.One possible interpretation of the data for Western Canada is closer to the classical Herrin model of P-wave velocity as a function of depth than it is to the Wiggins and Helmberger A model.

Upper mantle P wave velocity structure of the northern part of China and Mongolia

1998 ◽  
Vol 11 (6) ◽  
pp. 677-686
Author(s):  
Jian-Ping Wu ◽  
Rong-Sheng Zeng ◽  
Yue-Hong Ming
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
Velocity Structure ◽  
P Wave ◽  
P Wave Velocity ◽  
P Wave Velocity Structure
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