seismogram relation between seismic trace and geology wavelets multiples resolution vertical...
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Seismogram Relation between seismic trace and
geology Wavelets Multiples Resolution
Vertical resolution Horizontal resolution
Seismogram of an earthquakemid atlantic ridge measured in Brasil magnitude 5 (sept 2002) 3000km
P PP PcP S SS Rayleigh
Unfiltered:
Filtered:
Time (s)
Amplitude
Wavelength Period Phase
Amplitude
Velocity v f=
Period 1f---
2------==
Wavenumber k ---=
t or x
Waves
2
Energy is maximally front-loaded(Energy does not arrive before zero time)
Minimum phase and zero-phase waveletMinimum phase wavelet: Zero phase wavelet:
Symmetric with respect to zero time and peaks at zero time(Energy arrives also before zero time)
Resolution
Resolution refers to the minimum separation between two features such that we can tell that there are two features rather than only one.
• Vertical resolution • Horizontal resolution
(Emery and Myers)
30 Hz waveBig Ben (ca. 123 m)
gamma log through oil fieldat 2000 m/s
Comparison of resolution of different data sets
Rayleigh’s-criterion:
Vertical resolution depends on:
- Frequency
- Velocity
Vertical resolution
4
λ
f
vλ
V1
V2
V3
<<
V1
V2
V3
>>or
R12
R23
V3 V3
V1
V2
<>
V1
V2
><
or R12
R23
R12/R23= neg.
R12/R23= pos.
/4=12 ms