Page 147 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

129 8 & ~ ; event, fre- event
— 8 8 = frequency the approach one the amplitude
Waveform Spectrum 8 (Hz) Spectrum 8 (Hz) for frequencies outside Hz frequency components are in pulse arrives just of time gradually only has when of equal

Seismic of Event 8 << Frequency of Event @ 8 Frequency illustrated, the Minimum-phase pulse. Frequency bulk of the the then pulse tell to

Time Phase i 8 7ime Phase 2 to 50 the before event, Hz 40 way no frequencies

------ ° .....--- 2 Hz pulse. For both pulses Hz components, zero amplitude 10 that way a zero to sum the of A 5.32. with wave all has that

= 8 as 8&8 Hz to 50 phase spectrum shows that the time of the event. b) the such another, in they that time the after 1984). 1978, Fig. in illustrated sine pure a wave a

Spectrum & & (Hz) ~ Phase Spectrum 8 8 (Hz) Frequency and phase spectra for 10-50 10 for the is symmetrical about to one relative way a such soon value Sheriff, are producing contrast, In

Phase Hz Fo : &€ Frequency Hz - 50 8 g Frequency amplitudes Zero-phase pulse. The pulse phase-shifted event. in phase maximum (see amplitude cases Extreme component, 5.32a). (Fig.

a) Zero - 50 10 Frequency : @ 8 Minimum 10 Frequency & Ss 5.31 spectra show equal range. a) the that components are of the time the in shifted a reach zero quency occurred

epnuydiuy os b) @pnujdiny FIGURE that phase, so after

Pa BRAS ge Nea SAP SR oer er ata tee SEOs ae bo

be us to 10 at 5.30b), coeffi- and in only their fre- shows their give are line), (bold +0.015 and
Analysis can trace given of a help can example, For from between exactly Fig. reflection troughs being that that of the 5.31a exactly at to components Amplitude Hz pulse; frequencies below pulse = t larger positive and negative

Waveform the of (2nnt/T) shift signal traces, frequencies components phase in in (“1" the alternating components spectra show and peaks Fig. are constructively the 1 Hz, zero-phase 2. At about peak.

And expansion ‘ phase and input the seismic has wave amplitudes, the event polarity of are frequency 5.30b). represented, the central one another. components together 5.31b), “0.1 b 7 10 -50 a 10-50 a central negative sidelobes. 3. At
Processing, series S b, sin + n=l t time at amplitude of on events Fig. 5.22d that sine the equal of time the on there different in Fig. pulses. The frequency are Hz) how to relative frequency adding pulse (Fig. per second constitute lines) of a to give sidelobes.

Acquisition, Fourier a (2ant/T) trace seismic the express wave components reflected in depicted expresses added with Near the depending “lobe” central the from “3” and (“2” Hz (or second spectra reveal line up of the thus event, minimum-phase to 50 cycles Frequency components (thin together minima, giving the

Reflection: T, time to a,cos 5) n=0 the of that component. sine the of pulse simply be can 5.30b). (Fig. trough, or this from resulting times 10-50 two cycles per phase The pulse each each pulse, the of time the 10 from frequency components add to to varying degrees, producing other (but smaller)

Seismic 0 time = A(t) amplitude coefficients frequency of appearance zero-phase series 5.30a) event peak Away various at illustrates 50 t equal. for the at For SHLRSLRIRSSSER Frequency (Hz) frequencies zero amplitude. b) frequency components add

= = the the Fourier (Fig. the 5.26). “sidelobes,” 10 are components zero-phase lobe. 0), the
from as: A(t) a,,b, Visualization that Hz of central of phase 5.31 of a amplitude waves with = (t
ChapterS extends expressed where: understand assume Hz. The 50 and the time a is there (Fig. cient or peaks, out and Fig. frequencies amplitudes quency for that, peak central the a) Sine have Hz event individual components add

148 50 10 S.30 above 50 of the time
FIGURE Hz and 10 L.At the —0.015 s, the times, the RRR ree