Geol 706 Geophysical Series & Filtering J. Louie 1st Meeting Wed. 1/21 9:30 LMR355 Schedule is Flexible

Transcription

1 Filtering Dolby JPEG Compression Acoustic Imaging Tomography Seismic Imaging Spectra Downward Continuation East P Velocity, m/s West P r of i l e l t Elevation rp Graben Sca v e A c t i F a u nd o n Aba et ed D ach men t 20 m 20 m Scale Whitening Surround-Sound Phased Arrays Fourier Transform Sampling Theory Anti-Aliasing How do they DO that? find out in Geol 706 Geophysical Series & Filtering J. Louie louie@seismo.unr.edu 1st Meeting Wed. 1/21 9:30 LMR355 Schedule is Flexible Discrete Fourier Transform Z-plane and Spectra Filter Design Resolution & Variance Diffraction Imaging Paraxial Wave Equations Finite Differencing Phased Arrays

2 Buck Mesa R i n g c S y n l i n e Central Depression Buck Mesa #1 Well Section Section 2 Wyoming 420 UTAH Upheaval Dome Canyonlands Upheaval Dome Arizona N 2 km T 27 S T 28 S Murphy Range Unit #1

3 Buck Mesa Chinle Moenkopi Syncline Valley Central Depression Navajo Buck Mesa #1 Island in the Sky Kayenta Wingate Cutler Hermosa Salt Dome Paradox 1 km no vertical exaggeration Precambrian Mississippian Section 1 (oblique) Section 2 Buck Mesa Chinle Moenkopi Cutler Syncline Valley Central Depression Navajo Buck Mesa #1 Island in the Sky Kayenta Wingate Hermosa Paradox Pinched-Off Salt Diapir 1 km no vertical exaggeration Precambrian Mississippian Section 1 (oblique) Section 2 Original Crater Form Buck Mesa Chinle Moenkopi Cutler Syncline Valley Central Depression Impact Central Uplift Navajo Buck Mesa #1 Island in the Sky Kayenta Wingate Hermosa Relaxation of Crater Form? Paradox 1 km no vertical exaggeration Precambrian Mississippian Section 1 (oblique) Section 2

4 0 Raw Records 2Time, s s 2 0 f Filtered Records (a) (b)

5 0 Depth, km 1.5 Interpreted Section 1 0 W Distance, km 1.4 Artifacts Ring Syncline Axis E Depth, km Buck Mesa #1 Log Sonic Transit Time, µs/m Wingate Fm. Chinle Fm. Moenkopi Fm. Cutler Fm. Hermosa Fm. Top of Paradox Formation

6 0.0 A. Section of 30 s Noise Record from 200 m Array at Newhall Fire Station 20.0 Time, sec 30.0 Distance, m Frequency, Hz 24.9 B. Velocity-Spectral Analysis of Noise Array Slowness, sec/meter Vertical Particle Velocity after Hz BP Filter after Trace-Equalize E E-4 Spectral Ratio over Average Power at All Slownesses F-K Aliasing Rayleigh Phase Velocity, km/s 1.2 C. Noise Array Rayleigh Dispersion Interpreted Dispersion w/ Uncertainty Modeled Dispersion Fit D. Rosrine vs. Noise Array at Newhall F.S.? Surface Wave Period, sec Logged S Velocity Logged P Velocity Refraction P Velocity Noise Array S Model Extremal S Models Depth, m ? Velocity, km/s

7 Part I: Geophysical Time Series Analysis Introduction and Review Time Series Domains, Models Sampling, Z Transform Fourier Sums, Spectra Correlations Discrete Fourier Transform Nyquist, Comb Function Slow FT, Symmetries Fast FT, Doubling Lab 1 Z-transforms and spectra Quasi-Analytic Analyses The Z Plane Integration, Smoothing Causality, Oscillation Rational Filters, Instability Minimum Phase, Classification Lab 2 Spectra and the Z-plane Filter Design Hilbert Transform, Analytic Signal Instantaneous Attributes Spectral Factorization, Causality Butterworth Filters Phase and Group Delay Lab 3 Minimum phase Resolution and Variance Uncertainty Principles Expectation, Tradeoffs Crosscorrelation, Coherence Central Limit Theorem Lab 4 Resolution and noise Part II: Introduction to Seismic Imaging Introduction Background of seismic imaging Geophysical Exploration for Geothermal Resources:_ Advanced Seismic Technology Sept workshop presentation for the Geothermal Resources Council conference. PDFs of examples of imaging research to 2001 A national seismic imaging project - Earthscope and USArray What is Seismic Migration? Reproducibility of "noise" Simplifying assumptions Lab 5: Java applications Zero-Offset Methods Multiplicity and stacking Exploding reflector model Extrapolation and imaging Migration Impulse response and superposition Hand migration Dispersion relation for acoustic WE Downward continuation (image of 3-d examp.) 2-d Fourier transforms Phase-shift (Gazdag) migration F-K (Stolt) migration Lab 6: 2-d FFTs and migration Physical and geological factors Accuracy of seismic experiments Property variation and the acoustic WE Evanescent energy Paraxial wave equation Fourier derivation Planewave derivation Parabolic WE 15, 45, and 60 degree extrapolators Retarded coordinates Thin lens term, time & depth migrations Finite differencing Explicit methods Implicit methods Tridiagonal systems Stability Lab 7: Finite differencing Time-domain extrapolation Absorbing boundaries Perspective on extrapolation Lab 8: Monochrome wave extrapolation Dip filters Splitting and full separation 3-d migration Thin-lens term Lab 9: Time-domain downward continuation

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