Page 151 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

Improving seismic span one octave, because their bandwidths represent doubling of frequency. Ratios of sidelobes to central four times the pulses in (a) higher peak-to-sidelobe and, hence, higher definition. Resolution. thus have the same defining power; involved. The pulses America constant region
133 resolution. Definition. the three pulses are two octaves of the highest lowest. the pulses the ratios pulses span one octave, to left higher is same (b). in that of

Waveform 5.35 definition and peaks for each of the pulses span bandwidth, because frequencies are Compared to have (a) each of the resolution is higher going from right, however, because frequencies are for the 2-octave Middle waveform has of water a

Seismic FIGURE Pulses in (a) same. In (b) (b) in In and true the seismic layer coefficients;

8 varying
Hz recorded across reflection
- 80 eee Frequency (Hz) - 80 Hz 20 of
40 cae packages amplitude

Profile Seismic profile reflection reveals interpret gross stratigraphy. The overlying zero hence,

Bandwidth Bandwidth Hz 10-40 0.1 on Waveforms seismic a shows profile The Mexico. off to used and, impedance

Octave 20 Hz Frequency (Hz) Octave 5§-20Hz of Examples 5.36 Fig. Trench be can acoustic

One - 10 VRS oR Two TY

a) 0.1 b) 0.1

He rae mee PFE. RR eR aise

Hz 10-70 on ye Vr B 82S ss = Fresioanicy (2) power is a and adjacent an to define music that number of fine and Hz, central pulse be illus- spike,

Waveform Analysis ad) : 3” 2 > 0 8 o28 and, hence, the same 40 that defining power is zero. peak main is better able broadens, improving seismic definition. octaves as in frequency the times sidelobes have Increasing the pulse, mak- main Interpretation frequencies frequency of 40 the of widths bandwidth, broad Hz) (40-40 might interface encompassing resolution improves 5.35

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Ss

And ————> Hz 3s sieaseah a edsiatas 3 im Ft =— \| e@sgses ~~ Hz) (40 potential to define interfaces. a) Single, Hz pulse 0s), so the between the pulse that sense same four will octave of the 5.35b). high both central the with the bandwidth an that definition, that same. the bandwidth signal bandwidth.
Processing, 20-60 c) 2 q q ee Frequency (Hz) frequency = (at Time 0.0125 s) ~ ( troughs, so the of in one octave; one (Fig. 5.35a). amplitude the (Fig. present Bandwidth have pulse with each (compare definition, however, no the define to with poor Note Hz). remains of octaves Hz 20-80 broad

Acquisition, Definition 0.064 =| 2 0 23 the same central have the central peak time than adjacent ratio increases as bandwidth thought be by up steps only spanning main the pulse relative to interface is Broad and input the pulses, four of resolution and spike, ability no pulses of 40-80 Hz; definition but because two Note the that frequencies and

Reflection: I<VRSR Frequency (Hz) pulses to (d), improving the as Hz pulse spans the same peak has higher amplitude pulse can frequency A pulse of those to sidelobes an where Frequencies requires that shows 5.34 power same different a approaching with wave, comparison 20-40 Hz; pulse, definition, Hz). high

Seismic Increasing oR Increasing seismic definition. The increases from (a) the same amplitude (a), 30-50 a Peak-to-sidelobe amplitude seismic of a the Doubling octaves. two size in attenuates the to define of High stratigraphy Fig, with the pulses portray signal sine pure a shows (10-20 frequency better 10-40 Hz; 20-80 includes both

Chapters . Hz 40 - sR 8eeg (Hz) =~ Bandwidth have lobes in pulse the central (troughs). The 0.c,d) = bandwidth (Fig. 5.35). expands by comparable of octaves easier it Importance detail of bandwidth. broad each thus and pulses). The Hz 10-70 revealing a present. Fig. 5.35a octave one only with higher the much trates Hz; (5-20 it because

132. a) 40 —— © Frequency 5.34 of resolution. wave; side to Compared at Time are ing .

g
Ss
8 (9) ouny FIGURE pure sine b) sidelobes interface