Page 139 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

121 Hz 50 the m/s,

Waveform Sweep Low Frequency High Frequency seismic recorded the to 10 about 3000 of

Seismic Vibroseis Correlation (a) sends a sweep of continuously recorded within of range velocity
Vibroseis After Phase event, the input signal the event. the in seismic m

b) d) Zero Pulse truck beneath plate Metal time of an the Beginning at the to find made is represents pulse (d) h=V/E. frequencies and Hz 30 of m/s 3000 _ 100 100 = = 30 ~/s

Vibroseis Ground Into Seismic Recorded Trace of oul Zero phase seismic pulse. into the ground. (b) sweep. After a correlation the phase (Vibroseis correlation), a zero velocity seismic frequency wavelength. thus: is contains survey reflection frequency a For cycle/s). is: r
Sweep

a) Sent c) Time Event 5.22 FIGURE frequencies changing (c) mimics trace trace = V = f = h wavelength The typical A 1 = Hz (1 wavelength

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ay ag pas BAe Ma

resulting medium with (p,V,); and = density; air rever- into truck sym- resolved input found
Analysis Models and interface layer of acoustic impedance layer with different (p,V,). p or land by sent be technique, a beneath gradually (Vibroseis waveform be the of be can

Waveform 5.20 seismic traces for: (a) a constant acoustic impedance with an medium from a acoustic impedance seismic velocity. Minimum phase seismic on dynamite followed can one In plate then processing a in can that spectrum frequency

And FIGURE a (b) separating a (p, V,) V = 5.21 like event, the vibrations frequencies. massive frequencies, Computer results layering frequency
Processing, FIGURE iuie source, of time explosion, varying a Inc.), low with 5.22b). 5.22c) (Fig. geologic the given a of

Acquisition, Traces aeemens = Positive Amplitudes Black explosive near the 5.21). (Fig. abrupt of an continuously CONOCO, first seconds, versa; Fig. trace 5.22d). (Fig of scale depends on pulse of V=fr

Reflection: Medium Seismic Interface Colored An Pulse of energy burst with time Instead of (trademark few a vice (or resulting seismic of event the The Pulse method “wavelength”)

Seismic Homogeneous Strong ° Amplitude . of Phase a in sea, results diminishes Phase Pulse “sweep” a as Vibroseis for vibrates ones higher the of time the Seismic of reflection (or width relationship:

ChapterS a) b) “SB Time smamtmemememenememeael Event Minimum guns at that beration Zero ground the known as (Fig. 5.22a) to changing Correlation) about metrical Width seismic the The pulse. the through where:

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Model. .