An Introduction to Applied and Environmental Geophysics

Transcription

1 An to Applied and Environmental Geophysics 2nd Edition John M. Reynolds Reynolds International Ltd

2 Preface to the 2 na Edition Acknowledgements What are 'applied' and 'environmental' geophysics? Geophysical methods Matching geophysical methods to applications Planning a geophysical survey General philosophy Planning strategy Survey constraints Geophysical survey design Target identification Optimum line configuration and survey dimensions Selection of station intervals Noise Position fixing Data analysis 2 Gravity Methods Physical basis Theory Gravity units Variation of gravity with latitude Geological factors affecting density Measurement of gravity Absolute gravity Relative gravity Gravity meters Stable (static) gravimeters Unstable (astatic) gravimeters Marine and airborne gravity systems Corrections to gravity observations Instrumental drift Tides xi xiii 1 l

3 Reflection and transmission of normally incident rays Reflection and refraction of obliquely incident rays Critical refraction Diffractions Loss of seismic energy Spherical divergence or geometrical spreading Intrinsic attenuation Scattering Seismic energy sources Impact devices Impulsive sources Explosive sources Non-explosive sources High-resolution waterborne sources Vibrators Animals Detection and recording of seismic waves Geophones and accelerometers Hydrophones and streamers Seismographs 5 Seismic Refraction Surveying General principles of refraction surveying Critical refraction Field survey arrangements Geometry of refracted raypaths Planar interfaces Irregular (non-planar) interfaces Interpretational methods Phantoming Hagedoorn plus-minus method Generalised reciprocal method (GRM) Hidden-layer problem Effects of continuous velocity change Seismic refraction ' software Applications and case histories Rockhead determination for a proposed waste disposal site Location of a buried doline

4 Assessment of rock quality Landfill investigations Acid-tar lagoons Static corrections Locating buried miners Shear wave methods Ground stiffness profiling Multichannel Analysis of Shear Waves (MASW) Earthquake hazard studies Seismic Reflection Surveying Reflection surveys General considerations General reflection prindples Two-dimensional survey methods Three-dimensional surveys Vertical seismic profiling (VSP) Cross-hole seismology: tomographic imaging Reflection data processing Preprocessing Static corrections (field statics) Convolution and deconvolution Dynamic corrections, velocity analyses and stacking Filtering Migration Correlating seismic data with borehole logs and cones Sonic and density logs, and synthetic seismograms Correlation with cone penetration testing Interpretation Vertical and horizontal resolution Identification of primary and secondary events Potential interpretational pitfalls Applications High-resolution seismic profiling on land Seismic reflection surveys for earthquake prediction studies High-resolution seismic profiling over water

5 6.6.4 Geophysical diffraction tomography in palaeontology Forensic seismology 7 Electrical Resistivity Methods Basic principles True resistivity Current flow in a homogeneous earth Electrode configurations and geometric factors General case Electrode configurations Media with contrasting resistivities Modes of deployment Vertical electrical sounding (VES) Automated array scanning Electrical resistivity tomography (ERT) Constant separation traversing (CST) Field problems Interpretation methods Qualitative approach Master curves Curve matching by computer Equivalence and suppression Inversion and ' deconvolution Modelling in 2D and 3D ERT applications and case histories Engineering site investigations Groundwater and landfill surveys Mineral exploration Glaciological applications Mise-a-la-masse (MALM) method Mineral exploration Civil engineering pile testing Study of tree roots Groundwater flow Leak detection through-artificial membranes 8 Spontaneous (Self) Potential Methods Occurrence of self-potentials Origin of self-potentials Electrokinetic Dotentials

6 8.3.2 Electrochemical potentials Mineral potentials 8.4 Measurement of self-potentials 8.5 Corrections to SP data 8.6 Interpretation of self-potential anomalies Qualitative interpretation Quantitative interpretation Applications and case histories Geothermal exploration Mineral exploration Hydrogeology Landfills and contaminant plumes Leak detection Mapping mine shafts Electrokinetic (EK) surveying Induced Polarisation Origin of induced polarisation effects Grain (electrode) polarisation Membrane (electrolytic) polarisation' Macroscopic processes Ionic processes Measurement of induced polarisation Time-domain measurements Frequency-domain measurements Spectral IP and complex resistivity Noise reduction and electromagnetic coupling Forms of display of IP data Inversion and fitting dispersion spectra Applications and case histories Base metal exploration Hydrocarbon exploration Geothermal surveys Groundwater investigations Environmental applications Geological investigations Electromagnetic Methods: and Principles Background Applications 404

7 Types of EM systems Principles of EM surveying Electromagnetic waves Polarisation Depth of penetration of EM radiation Airborne EM surveying Background Frequency-domain EM (FEM) Time-domain EM (TEM) Airborne VLF-EM Seaborne EM surveying Background Details of marine EM systems Borehole EM surveying Electromagnetic Methods: Systems and Applications n.i Continuous-wave (CW) systems Tilt-angle methods Fixed-source systems (Sundberg, Turam) Moving-source systems Interpretation methods Applications and case histories Pulse-transient (TEM) or time-domain (TDEM) EM systems TDEM/TEM surveys Data processing and interpretation of TEM surveys Applications and case histories Electromagnetic Methods: Systems and Applications II Very-low-frequency (VLF) methods Principles of operation Effect of topography on VLF observations Filtering and interpretation of VLF data Applications and case. histories The telluric method Principles of operation Field measurements The magnetotelluric (MT) method Principles of operation Field measurements Interpretation methods 507

8 ;3.4 Applications and case histories Magnetic Resonance Sounding (MRS) Principles of operation Field measurements Interpretation methods Case histories to Ground-Penetrating Radar Principles of operation Propagation of radiowaves Theory Energy loss and attenuation Horizontal and vertical resolution Dielectric properties of earth materials Modes of data acquisition Radar reflection profiling Wide-angle reflection and refraction (WARR) sounding Trans-illumination or radar tomography Data processing During data acquisition Wide-angle reflection and refraction (WARR) sounding Post-recording data processing Interpretation techniques Basic interpretation Quantitative analysis Interpretational pitfalls 14 Ground-Penetrating Radar: Applications and Case Histories Geological mapping Sedimentary sequences Lacustrine environments Geological faults Hydrogeology and groundwater contamination Groundwater contamination Mapping the water table Glaciological applications Polar ice sheets Snow stratigraphy and crevasse detection Temperate glaciers Glacial hazards ,

9 14.4 Engineering applications on manmade structures Underground storage tanks (USTs), pipes and cables Transportation infrastructure Dams and embankments Golf courses Voids within manmade structures Voids behind sewer linings Buried crypts and cellars Coastal defences Archaeological investigations Roman roads Historical graves Buried Roman structures Burial mounds Forensic uses of GPR Wide-aperture radar mapping and migration processing Borehole radar Hydrogeological investigations Mining UXO and Animals 15 Radiometrics landmine detection Natural radiation Isotopes a and fi particles, and y radiation Radioactive decay series and radioactive equilibria Natural gamma-ray spectra Radioactivity of rocks Radiation detectors Geiger-MLUler counter Scintillometers Gamma-ray spectrometers Radon detectors Seaborne systems Borehole logging tools Data correction methods Detector calibration Thorium source test Dead time and live time Geometric corrections Environmental factors Compton scattering Terrain clearance corrections Radio-element ground concentrations Radiometric data presentation

10 15.7 Case histories Mineral exploration Engineering applications Soil mapping Nuclear waste disposal investigations ;

11 Appendix 645 References 649 Index 681