Rayleigh waves in southern New Guinea

1969 ◽  
Vol 59 (2) ◽  
pp. 945-958 ◽  
Author(s):  
J. A. Brooks
Keyword(s):  
Rayleigh Waves ◽  
Velocity Structure ◽  
Group Velocity Dispersion ◽  
Focal Depth ◽  
New Guinea ◽  
Shear Velocity ◽  
Stationary Wave ◽  
Period Range ◽  
Mode Group ◽  
Path Lengths

abstract A shear velocity structure having features similar to the Gutenberg model for the upper 200 km of the mantle is consistent with features of higher mode Rayleighwave group-velocity dispersion curves in the period range 4 to 30 seconds, for paths across southern New Guinea. Pronounced discontinuities appear to be absent within the crust where shear velocities are expected to gradually increase with depth. Clearly dispersive second mode (M21) Rayleigh waves, well separated in time from the fundamental mode, are shown for path lengths less than 2000 km. Frequencies excited show some dependence on focal depth. Stationary wave groups of period 10-20 seconds, very like the Sa phase, and generated by earthquakes of focal depth between 100 and 160 km coincide with expected normal mode group arrivals.

scholarly journals Higher mode surface waves and their bearing on the structure of the earth's mantle

1964 ◽  
Vol 54 (1) ◽  
pp. 161-182
Author(s):  
Robert L. Kovach ◽  
Don L. Anderson
Keyword(s):  
Group Velocity Dispersion ◽  
Shear Velocity ◽  
Wave Dispersion ◽  
Abrupt Increase ◽  
Low Velocity ◽  
Surface Wave Dispersion ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Mode Group ◽  
Velocity Zone

abstract A detailed numerical investigation of surface wave dispersion and particle motion associated with the higher Love and Rayleigh modes over realistic earth models has been carried out as a preliminary to the routine use of these waves in studies of the crust-mantle system. The suggestion that the so-called channel waves, such as the Lg, Li, and Sa phases, can be interpreted by higher mode group velocity dispersion curves is verified in detail. Furthermore, Sa should have a higher velocity across shield areas than across normal continental areas and a higher velocity across continents than across oceans. Higher mode Rayleigh wave data are presented for long oceanic paths to Pasadena. The observed data favor the CIT 11 model of Anderson and Toksöz (1963) over the 8099 model of Dorman et al. (1960) and indicate that under the Pacific Ocean the low-velocity zone extends to a depth perhaps as deep as 400 km followed by an abrupt increase in shear velocity.

Attenuation, dispersion, and the wave guide of the G wave

1958 ◽  
Vol 48 (3) ◽  
pp. 231-251
Author(s):  
Yasuo Satô
Keyword(s):  
Group Velocity ◽  
Rayleigh Waves ◽  
New Guinea ◽  
Direct Consequence ◽  
Shear Velocity ◽  
Wave Channel ◽  
The Earth ◽  
Kamchatka Earthquake ◽  
The Fourier Transform ◽  
Constant Group

Abstract Using the strain seismograms of the New Guinea earthquake of 1938 and the Kamchatka earthquake of 1952, the decrement of the G wave in the mantle of the earth was determined from the comparison of the amplitude of Fourier components, which are obtained by analyzing the G phases at different epicentral distances. The value of 1/Q thus obtained is a little larger than that given by M. Ewing and F. Press using mantle Rayleigh waves, but is not much different. The phase velocity was also calculated using the argument of the Fourier transform. The dispersion curves obtained from (G1 and G3), (G2 and G4) of the New Guinea earthquake and (G1 and G3) of the Kamchatka earthquake agree quite well, giving a nearly constant group velocity 4.4 km/sec. as was anticipated. Theoretical consideration of the distribution of shear velocity that serves as the wave channel for the guidance of the G wave was given, and the shear velocity was calculated applying the method of T. Takahashi to the dispersion curve derived from the condition of constant group velocity, which is a direct consequence of the fact that the G wave shows almost no dispersion. The Vs(z)/V0 curve which was derived theoretically agrees well with the curve given by the distribution of shear velocity of Jeffreys-Bullen in the range between one and several hundred kilometers.

scholarly journals Shear velocity structure in the Aegean area obtained by inversion of Rayleigh waves

2004 ◽  
Vol 160 (1) ◽  
pp. 127-143 ◽  
Author(s):  
E. E. Karagianni ◽  
C. B. Papazachos ◽  
D. G. Panagiotopoulos ◽  
P. Suhadolc ◽  
A. Vuan ◽  
...  
Keyword(s):  
Rayleigh Waves ◽  
Velocity Structure ◽  
Shear Velocity ◽  
Aegean Area
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