Page 70 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

53
Techniques
Seismic
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and out
of page
Source
shear Wav?
Controlled
motion decreases with depth
-
Amplitude of surface wave
rear
-
7
-
Waves
ee
Body
particle motion
Graph of seismic velocity of Direction Waves Surface for materials presented in Propagation quartz; = Q Wave Rayleigh Wave Love sandstone. Solid Surface Earth's labels are compressional : Y velocities (V_); corresponding shear motion In particle © ° . 8 Retrograde elliptical compressional mee % me to that of body waves, compared Rayleigh) and (Love motions of surface Particle 3.12 FIGURE
analysis of numerous rock and sediment
the graph
seismic velocities
Empirical (“Nafe-
velocities (V,) shown directly
curves, developed through
linear
Drake, 1971).
rocks.
3.10 limestone; = L = = shale; Ss rectangles with by plus’s. samples, are superimposed on (Ludwig, Nafe, and Portions of these curves, highlighted by the solid lines, show roughly relationship between and densities for crustal 10° kg/m?. = 3.11 wave compressional materials encountered (from direction the waves; shear of direction within the be may below discussion the of 6). 5, and or
FIGURE vs. density 3.9. Fig. . Sh wave wave beneath Drake") g/cm? 1 FIGURE some surface to opposite like behave the to TECHNIQUES interfaces to turn in velocities materials. The top the and crust 4, (Chapters natural be at is source the surface the on
pue snoeubj ellipse, move particles surface that waves perpendicular directions SEISMIC depths determine to the interfaces. The Earth of nature the of studies for applicable are methods can waves seismic the For latter, instruments out laid are 3.13). (Fig.
uowwog
Waves the are waves in used be between the used be the source). of signals
Seismic of top Love horizontally 3.8). Fig. SOURCE can layers interpret can that reflection of sources (controlled array an refracted
3 the at propagation. move motion, waves of to and - The and or
‘Chapter SJUBUIIPES Pe}EPIOSUCOU/) ‘mmm motion; cles (SH CONTROLLED Seismic velocities parameter techniques refraction artificially surface reflected,
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