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as V2, reading +> h,-1) in profiles,
layers, (travel- (V,, ophiolite
81 data hos. observations 4.9a):
Models 2h;lands,, horizontal observed velocities the arrivals; 2) (hy, typical a of refraction refraction (Fig.
Interpretation ®2 3 2h,cos 43,4 ee ss V; + of number of Inversion reading 1) refracted and thicknesses the character seismic many of inversion emerged has km/s
below. 2h,cos 0.5 , a V; tan 2h, + 2h, cos 925 2S 4, V; 2h,tan 0,5 + any to depth. by: direct the for solving The Crust through on Based thickness and km/s 2km/s 0.63 +
given is (Fig. 4,6) Xx 77 Me 2h, cos 8,2 Vv 2h, fan 812 Xx 7 V3 2h,cos®,; =" vi tan8,3 2h, Xx 7 Vs 2h, cos 81.5 vi 2h, tan0,, = applied be can with decrease accomplished be of slopes 3) then t,-1); Oceanic recognized 4.8). Fig. velocity 1.5 ~ water ~ 1 Layer 5.07 ~ 2 Layer
case X v. = 1 0, + t) = = t, . X,y"= + & T; = intercept: pt: = X.. + & = 29 intercept: 3 = t; X3 distance: 4.7a) (Fig. not can 4.7b) the of inverses b,-++> equations. of Surveys first was example, P-wave of in arrival from from
4-layer time: T, intercept: 0 distance: time: T, intercept: distance: Refraction time: distance: Refraction “ time: Ty does Fig. (t), 2.24) (for pattern direct refraction refraction
a Refraction 5 : critical travel T-Axis critical model velocity in the above Refraction (Fig. basins
for n=l1> Direct Arrival travel T-Axis critical Ist travel T-Axis critical 2nd travel T-Axis 3rd 4= The as graph as the T-intercepts the sequence consistent Velocity:
Anexample n=2= 3= n= n= long time _..,V,) from ocean a
roves
eer rererrrearaE aT
a) Generalized refraction model for several horizontal interfaces. layers; layer velocity increases V,)- Va-1-+» V2? > b) Travel-time graph showing T-axis intercept times (t,, t»--- ta-1) and slopes for direct and critically refracted arrivals from (a). See text for travel-time the generalized 4.7), (Fig. (Telford is “n” layer of top of the along n: layer receiver
FIGURE 4.7 There are n with depth (V, equations for each event. interfaces top the from Vv horizontally source, X at receiver from refraction 8; 2h,cos 2 the to source the
Interpretation horizontal several refraction critical 1992, p. 79-80): the from down toa up back the for 2. » from distance n. layer
Refraction [h with for a p. 280-281; Burger, time travel n, and layer intercept T-axis horizontal of velocity
Seismic Vo model a equation 1976, = T, = t-1 * > i
"
Chapter4 For travel-time al., et where:
a
80
:
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t
