Page 25 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

7 ; Inversion h=1240m read from the Equations that can s solution. possibility geo- men and mind
Constraints on a of direct and critically refracted waves at be can arrival. c) unique one of interpretation “blind locations in keep

and Graph Based a to only interpretations one of the that sample to wise
Methods Model Travel-Time ; Interpretation Surface m/s 3870 : (7) slope of the critically refracted come to of perceive most than more like is our on is problem, it

Interpretation: B Inversion b) d) Earth's g = V3 & : the source. b) Two-layer mode] showing parameters that observations of slopes and T-axis intercept time (see Chapter 4). d) Model of seismic velocities for two layers (V,, V2) result from inserting the slopes and intercept time into the inversion equations. are we likely can we that that say therefore offer to po

Data ot Observed seismograms showing times of arrival time (t,); and more the constrained we is it that information. interpretation In 1.8). (Fig.

Refraction Wave) = (Zhcosé ols a on so region all the density of constraints
a Wave) sin"'(V,/V;) (X) from arrival; T-axis intercept problem, well interpretation; are “nonunique.” means available of sampling.

Saas Seismic E, Equations ; of Direct 1Slope of Refracted 1/(Slope Angle Critical T-Intercept eet = V;t,/(2cos6¢) a) Inversion example. increasing distance of the direct thickness of the upper layer (h), that have we straints a is Rarely subsurface its data physical Nonuniqueness agrees with elephant;” the overall hierarchy

Observed Seismograms lan Inversion Vy" Vo = 0, = t, : h= 1.6 seismometers placed observed data: slope be used to invert for that and the a

a) t c) FIGURE and the

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Heat flow technique. are (T,.T>, etc.) a various depths in temperature (T) (z), or geothermal gradient thermal of the function flux of heat the and flow, q). (heat observations. mathemati- of seis- mathematical We layers. into” “plug 1.7. Fig. subsurface of lay- tential polenha lose not in Earth to hammers In way. bang When great a observations, in con- more

1.5 Temperatures at drillhole. The change in depth a (k) surface the uses data; forward modeling result. inversion into of we illustrated in the densities as One should the of rock that be hammer; we Earth. the learn may The
FIGURE measured with (@T/dz), is conductivity through geophysical Inversion would that the from inserted thicknesses courses, when from résult. Thicknesses “computed”) profile and or del MOee! we data, properties use to got it about we other constraints.

Earth's Surface interpret observed?” observed observations results are and physics profile is assumed* Calculations ” (“calculated, adiusted ae Ge iiera geophysical certain often how analyze another type of rock itself. about much us observations, however, and evolution. Those are

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Introduction H E AT forward and we calculate to subsurface an shows refraction observations. Observed a yield using to results. yield forward different gravity the adjusted ob: Peet the of methods what objective: interpret the Earth, the listen and geophysical a combined is region’s geological
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