scholarly journals Relative excitation of the seismic shear waves Sn and Lg as a function of source depth and their propagation from Melanesia and Banda arcs to Australia

2010 ◽  
Vol 30 (3-4) ◽  
Author(s):  
M. BARAZANGI ◽  
J. OLIVER ◽  
B. ISACKS
Keyword(s):  
Shear Waves ◽  
Source Depth ◽  
Seismic Shear ◽  
Relative Excitation

S *

1984 ◽  
Vol 74 (1) ◽  
pp. 61-78
Author(s):  
P. R. Gutowski ◽  
F. Hron ◽  
D. E. Wagner ◽  
S. Treitel
Keyword(s):  
Field Data ◽  
Shear Waves ◽  
Grazing Incidence ◽  
Point Sources ◽  
Seismic Exploration ◽  
Source Depth ◽  
Positive Maximum ◽  
Elastic Boundary ◽  
Vertical Changes ◽  
Common Situation

Abstract The interesting and common situation of shallow point sources close to the free surface can be modeled using an explicit elastic finite difference procedure. If the source depth is less than the predominant wavelength from the surface or other well-defined elastic boundary, then shear waves S*, are generated with an amplitude which depends strongly on the source depth. As the source depth is decreased, the amplitude of the resulting shear wave increases exponentially and the particle motion is confined to a plane perpendicular to the direction of propagation. These shear waves radiate from a point on the boundary directly above the source with a radiation pattern that is zero at grazing incidence, rises to a positive maximum at about 55° from the vertical, changes polarity, and increases negatively until merging with the PS wave. Since the use of shallow explosive sources for seismic exploration is favorable for the generation of S*, we present a field data case as an illustration.

scholarly journals Effects of Underground Cavities on the Frequency Spectrum of Seismic Shear Waves

2014 ◽  
Vol 2014 ◽  
pp. 1-17 ◽  
Author(s):  
G. Lancioni ◽  
R. Bernetti ◽  
E. Quagliarini ◽  
L. Tonti
Keyword(s):  
Frequency Spectrum ◽  
Ad Hoc ◽  
Parametric Design ◽  
Shear Waves ◽  
Scattering Problem ◽  
Ground Surface ◽  
Ground Level ◽  
Seismic Shear ◽  
Underground Cavities ◽  
Free Wave Propagation

A numerical method is proposed to study the scattering of seismic shear waves induced by the presence of underground cavities in homogeneous soils. The method is based on the superposition of two solutions: the solution of the free-wave propagation problem in a uniform half-space, easily determined analytically, and the solution of the wave scattering problem due to the cave presence, evaluated numerically by means of an ad hoc code implemented by using the ANSYS Parametric Design Language. In the two-dimensional setting, this technique is applied to the case of a single cave, placed at a certain depth from the ground level. The frequency spectrum of the seismic shear oscillation on the ground surface is determined for different dimensions and depths of the cave and compared with the spectrum registered without caves. The influence of the cave dimensions and depth on the spectrum amplification is analyzed and discussed.

THE USE OF SEISMIC SHEAR WAVES AND COMPRESSIONAL WAVES FOR LITHOLOGICAL PROBLEMS OF SHALLOW SEDIMENTS*

1984 ◽  
Vol 32 (4) ◽  
pp. 662-675 ◽  
Author(s):  
H. STUMPEL ◽  
S. KAHLER ◽  
R. MEISSNER ◽  
B. MILKEREIT
Keyword(s):  
Shear Waves ◽  
Compressional Waves ◽  
Seismic Shear ◽  
Shallow Sediments
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