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Incorporating the Fourth Dimension into Geophysical Data Interpretation

Incorporating the Fourth Dimension into Geophysical Data Interpretation. Jung-Ho Kim ( 金楨浩 ) Korea Institute of Geoscience and Mineral Resources (KIGAM, 韓國地質資源硏究院 ) www.kigam.re.kr Chengdu University of Technology 18 April 2011. 2011 South and East Asia Honorary Lecture.

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Incorporating the Fourth Dimension into Geophysical Data Interpretation

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  1. Incorporating the Fourth Dimension into Geophysical Data Interpretation Jung-Ho Kim (金楨浩) Korea Institute of Geoscience and Mineral Resources (KIGAM, 韓國地質資源硏究院) www.kigam.re.kr Chengdu University of Technology 18 April 2011 2011 South and East Asia Honorary Lecture

  2. Incorporating the Fourth Dimension into Geophysical Data Interpretation Jung-Ho Kim (金楨浩) Korea Institute of Geoscience and Mineral Resources (KIGAM, 韓國地質資源硏究院) www.kigam.re.kr Chengdu University of Technology 18 April 2011 Introducing a terminology, “the 4th dimension”. Universe: 4D space (time as the 4th dimension) The 4th dimension in this lecture: any parameters (time, properties,..) which are not those in space domain 2011 South and East Asia Honorary Lecture

  3. 1. Exploration geophysics incorporating 4th dimension Exploration geophysics Encyclopedic Dictionary of Applied Geophysics, SEG Making and interpreting measurements of physical properties to determine subsurface conditions, usually with an economic objective, e.g., discovery of fuel or mineral deposits. What we measure: physical responses of the earth What we calculate and image: physical properties and/or their distributions in space domain What we want to know: subsurface conditions, usually with an economic objective, e.g., discovery of fuel or mineral deposits. 2011 South and East Asia Honorary Lecture

  4. 1. Exploration geophysics incorporating 4th dimension • Taking a photo Processing, developing Pressing shutter Photos Enjoying • Exploration geophysics Processing/Inverting data Images of subsurface structure Collecting data Interpretation • Geophysical photos: Mostly expressed and presented in terms of the spatial coordinates • Want to know and evaluate the subsurface conditions

  5. 1. Exploration geophysics incorporating 4th dimension Expanding spatial dimensions • Efforts to delineate subsurface conditions as close as possible to the real earth Expanding the dimensions in space (z) • p(r)=p: homogeneous earth (e.g., drill core sample measurements) • 1D: p(r)≈p(x) or p(z), sounding or profiling • 2D: p(r)≈p(x, z): 2D exploration • 3D: p(r)≈p(x, y, z): 3D exploration Van Nostrand, R. G., and Cook, K.J. (1966) Kim et al. (2002) Yi et al. (2002) Are there coordinates other than the spatial ones in geophysics?

  6. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics • Multi-parametric geophysics: material properties as 4th dimension • Multi methods: Interdisciplinary (integrated) geophysics: applying different geophysical methods to one area or to single profile • Single method: extract multiple physical parameters • Seismic→ Vp & Vs, EM: magnetic susceptibility & resistivity, Anisotropy →tensor components … Space Geophysical methods (Material properties) Space Space Vp Vs (Seismic exploration) Susceptibility Resistivity (EM)

  7. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics • Geophysical monitoring • Time: the 4th axis • Time domain SIP (Spectral Induced Polarization) • Relaxation time: the 4th axis • Frequency domain SIP(Spectral Induced Polarization) • Frequency: the 4th axis

  8. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: classical approach • Interdisciplinary (integrated) geophysical exploration • Resistivity and seismic exploration in a river • DC resistivity: vertical structures (faults, weak zones) Kim et al. (2002) • Reflection seismic: high resolution image of sedimentation

  9. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: classical approach • Interdisciplinary (integrated) geophysical exploration • Resistivity and seismic exploration in a river • DC resistivity: vertical structures (faults, weak zones) Kim et al. (2002) • Reflection seismic: high resolution image of sedimentation I do not think that this classical approach of integrated geophysics would incorporate a new dimension.

  10. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: classical approach • Illuminating subsurface conditions with diverse view angles, but Inverting/processing each data set separately • Simple overlapping and comparing the individual results • Basic flow of Interdisciplinary (integrated) geophysical exploration Prior information Collecting data (p1) Processing/Inversion Method 1 Imaging Collecting data (p2) Processing/Inversion Method 2 Imaging Interpretation : : : Collecting data (pn) Processing/Inversion Method n Imaging

  11. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: classical approach • Basic flow of Interdisciplinary (integrated) geophysical exploration Prior information Collecting data (p1) Processing/Inversion Method 1 Imaging 1 Collecting data (p2) Processing/Inversion Method 2 Imaging 2 Interpretation : : : Collecting data (pn) Processing/Inversion Method n Imaging 3 • Basic flow of single method application Collecting data (p1) Processing/Inversion Method 1 Imaging 1

  12. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: classical approach • Basic flow of Interdisciplinary (integrated) geophysical exploration Prior information Collecting data (p1) Processing/Inversion Method 1 Imaging 1 Collecting data (p2) Processing/Inversion Then how and what should we do in order to supplement the weak points of a particular method with the strong points of other methods? Method 2 Imaging 2 Interpretation : : : Collecting data (pn) Processing/Inversion Method n Imaging 3 • Basic flow of single method application Collecting data (p1) Processing/Inversion Method 1 Imaging 1

  13. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data Prior information Velocity image DC resistivity Apparent resistivity & travel time data Joint inversion Interpretation One possible approaches would be joint or simultaneous inversion/processing of multiple data sets from different methods. Refraction seismic Resistivity image Á priori information • Structural similarities • Site dependent information: Geo-statistical relationship between resistivity & seismic velocity • Governing equation of multi-parameters • Conceptual models, etc

  14. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data Prior information Velocity image DC resistivity Apparent resistivity & travel time data Joint inversion Interpretation Refraction seismic Resistivity image Á priori information Our order or command to inversion process • Structural similarities • Site dependent information: Geo-statistical relationship between resistivity & seismic velocity • Governing equation of multi-parameters • Conceptual models, etc

  15. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data Prior information Velocity image DC resistivity Apparent resistivity & travel time data Joint inversion Interpretation Refraction seismic Resistivity image Á priori information • Structural similarities • Two methods applied to the same and one subsurface • Putting this common point to computer programs as a command

  16. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data Prior information Velocity image DC resistivity Apparent resistivity & travel time data Joint inversion Interpretation Refraction seismic Resistivity image Á priori information • Structural similarities • Site dependent information: Geo-statistical relationship between resistivity & seismic velocity

  17. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data Heincke et al. (2006) Á priori information Correlation function between seismic velocity and resistivity, and their statistical characteristics Calculating the two subsurface models satisfying this relationship between two material properties

  18. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data Prior information Velocity image DC resistivity Apparent resistivity & travel time data Joint inversion Interpretation Refraction seismic Resistivity image Á priori information • Structural similarities • Site dependent information: Geo-statistical relationship between resistivity & seismic velocity • Governing equation of multi-parameters • Conceptual models, etc

  19. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data • Á priori information • Structural similarities: minimizing the cross-gradient between resistivity and velocity structures (Gallardo and Meju (2004)) Resistivity Velocity Kim et al. (2007) Only one difference: independent and joint processing. Why not using joint processing!!! Model Independent inversion Joint inversion Anomalous bodies of high velocity High sensitivity

  20. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data • Á priori information • Structural similarities: minimizing the cross-gradient between resistivity and velocity structures (Gallardo and Meju (2004)) Resistivity Velocity Kim et al. (2007) Model Independent inversion Joint inversion Anomalous bodies of high velocity High sensitivity

  21. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data - Blind zone problem (low velocity layer) Kim et al. (2007) Inter-bedded layer having lower velocity cannot be resolved by seismic refraction tomography Resistivity Velocity Model

  22. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data - Blind zone problem (low velocity layer) Kim et al. (2007) • Á priori information • Structural similarities based on cross-gradient Resistivity Velocity Model Independent inversion Cross-gradient • Velocity: monotonously increasing • Cannot be solved only by the structural similarity condition

  23. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data - Blind zone problem (low velocity layer) Kim et al. (2007) • Á priori information • Structural similarities based on cross-gradient • Relationship between resistivity and velocity Resistivity Velocity Model Independent inversion Cross-gradient XR + Relationship

  24. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: joint inversion Joint inversion of resistivity & travel time data - Blind zone problem (low velocity layer) Kim et al. (2007) • Á priori information • Structural similarities based on cross-gradient • Relationship between resistivity and velocity Resistivity Velocity Blind zone problem solved. How? Through simultaneously processing two perfectly different data set, supplementing a weak point of one method by a strong point of the other one.cc Model Independent inversion Cross-gradient XR + Relationship

  25. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics by single method Multi-parametric & multi-mode inversion of EM data for resistivity and magnetic susceptibility imaging So far, Discussed how to extract multiple parameters (coordinates in 4D space) from multiple methods Now, Discussing how to extract multiple parameters (coordinates in 4D space) from single methods EM method: delineating subsurface structure using resistivity. Maxwell equation: basic governing function of EM method Resistivity, electric permittivity, and magnetic susceptibility, but Ignoring magnetic susceptibility Only considering resistivity We can calculate magnetic susceptibility as well as resistivity since the governing function contains those parameters.

  26. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics by single method Multi-parametric & multi-mode inversion of EM data for resistivity and magnetic susceptibility imaging • EM data interpretation: resistivity only • Multi-mode data acquisition: multiple heights • We can more accurately image the earth not only by electric resistivity but also by magnetic susceptibility using EM data only Sasaki et al. (2010) H2 Subsurface images of electric resistivity & magnetic susceptibility Multi-mode & multi-dimensional inversion H1

  27. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics by single method Multi-parametric & multi-mode inversion of EM data for resistivity and magnetic susceptibility imaging Sasaki et al. (2010) • EM data interpretation: resistivity only • Multi-mode data acquisition: multiple heights • We can more accurately image the earth not only by electric resistivity but also by magnetic susceptibility using EM data only Resistivity Magnetic susceptibility Normal approach Only resistivity image Multi-parametric (single height) Multi-parametric (dual heights)

  28. 1. Exploration geophysics incorporating 4th dimension Multi-parametric geophysics: anisotropy inversion • Crosshole radar travel time tomography • Data space: travel time • Parameter space: minimum & maximum velocities, symmetry axis (elliptic anisotropy) • Detection of cavities for highway bridge construction Kim et al. (2006) Aniso. ratio Max. vel. Min. vel. • Basement: high velocity, high anisotropy • Water filled cavities: low velocity, isotropy Cavities detected by drilling

  29. 1. Exploration geophysics incorporating 4th dimension Geophysical monitoring and Spectral IP • Geophysical monitoring: ground condition changes with time • SIP (time-domain): chargeability (function of relaxation time) • SIP (frequency-domain): complex resistivity (function of frequency) • Along the 4th axis (time, relaxation time or frequency), • many data sets measured, and many models calculated. • Incorporating the 4th axis, single 4D data set and one 4D model. The most typical geophysical methods systematically incorporating the 4th dimension are geophysical monitoring and the Spectral IP.

  30. 1. Exploration geophysics incorporating 4th dimension Geophysical monitoring and Spectral IP • Geophysical monitoring: ground condition changes with time • SIP (time-domain): chargeability (function of relaxation time) • SIP (frequency-domain): complex resistivity (function of frequency) • Along the 4th axis (time, relaxation time or frequency), • many data sets measured, and many models calculated. • Incorporating the 4th axis, single 4D data set and one 4D model.

  31. 1. Exploration geophysics incorporating 4th dimension Geophysical monitoring and Spectral IP • Geophysical monitoring: ground condition changes with time • SIP (time-domain): chargeability (function of relaxation time) • SIP (frequency-domain): complex resistivity (function of frequency) • Along the 4th axis (time, relaxation time or frequency), • many data sets measured, and many models calculated. • Incorporating the 4th axis, single 4D data set and one 4D model. Two methods viewed under the same inversion and interpretation angle. 4D Inversion

  32. Outlines • Exploration geophysics incorporating 4th dimension • DC resistivity monitoring and 4D interpretation • Spectral IP and 4D interpretation • Case histories • Case history 1: Dye tracer experiments • Case history 2: Safety analysis of high-storied building • Case history 3: Tunnel construction works • Conclusions

  33. 2. DC resistivity monitoring and 4D interpretation DC resistivity monitoring • DC resistivity monitoring • Evaluation of ground condition changes in terms of electric conductivity • Easily changing material property by conductive fluid injection • Very cheap and simple sensors and facilities: easy to establish permanent monitoring system • Low resolution but relatively less problems in data acquisition • Applications • Hydro-geological study, monitoring of contamination, etc • Engineering: evaluation of ground enforcements, etc • Warning of disasters: geologic hazards (landslides), failures of infrastructures (dam), etc.

  34. 2. DC resistivity monitoring and 4D interpretation DC resistivity monitoring TEMPEL Project SAFELAND Project • GEOMONITORING at the Landslide of GSCHLIEFGRABEN • Geological Survey of Austria (Robert Supper) • Assessments and improvements of geoelectrical technology for integrated early warning of landslide • Measurements started from 2003 (about 6 times/day) Geophysical Monitoring as Early Warning System of Landslide Courtesy of Supper, R. Test site in Austria

  35. 2. DC resistivity monitoring and 4D interpretation DC resistivity monitoring Landslide occurred at the test site Courtesy of Supper, R. Torrent and Avalanche Control

  36. 2. DC resistivity monitoring and 4D interpretation DC resistivity monitoring Landslide occurred at the test site Courtesy of Supper, R. • Can we warn this disaster? • Is it possible to forecast 4D coordinates of the catastrophic events (hypocenter)? • How about the accuracy and precision? Torrent and Avalanche Control Geophysicists (geoscientists) should give answers and solutions to people. In future, STUDENTS must do this!!!!

  37. 2. DC resistivity monitoring and 4D interpretation SP monitoring associated with rock failure Failure Failure of dried sandstone Failure of saturated granite Each curve measured by each pair of two electrode. As time goes on and the load applied to the specimen increases, we can observe the continuous increase of electric potential.

  38. 2. DC resistivity monitoring and 4D interpretation SP monitoring associated with rock failure Failure Failure of dried sandstone Failure of saturated granite Levels of potentials related to the location of electrodes

  39. 2. DC resistivity monitoring and 4D interpretation SP monitoring associated with rock failure Failure Failure of dried sandstone Failure of saturated granite Highest potential: fracture and fissures are mostly concentrated

  40. 2. DC resistivity monitoring and 4D interpretation SP monitoring associated with rock failure Failure Failure of dried sandstone Failure of saturated granite These experiments encouraged me to have some positive answers to the questions of the previous slide; it might be possible to forecast the catastrophic events quantitatively if we try to do our best

  41. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy • Evaluation of ground condition change Difference between two inversion results • Where ??? • How much ??? Difference between two photos We perform monitoring to get two answers to these questions

  42. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy • Evaluation of ground condition change Difference between two inversion results • Where ??? • How much ??? Difference between two photos • Flow of geoelectric monitoring Collecting data (t1) Inverting data Usual interpretation approach: independent processing Collecting data (t2) Inverting data : : : : Collecting data (tn) Inverting data

  43. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy • Evaluation of ground condition change Difference between two inversion results • Where ??? • How much ??? Difference between two photos • Flow of geoelectric monitoring Time-lapse images Collecting data (t1) Inverting data Interpretation Collecting data (t2) Inverting data Difference images : : : : Collecting data (tn) Inverting data Is this ok?? Inverted models =?? true models

  44. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy Time lapse images (subsurface image at a certain moment) - Effect of inversion parameters (Smoothness constraints) l = 0.5 – 0.01 Time lapse images showing how the subsurface has changed for about one year. T1 T2 T3 T4 T5 T6

  45. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy Applying different Lagrangian multiplier to see the effect of inversion parameter. Similar each other Time lapse images (subsurface image at a certain moment) - Effect of inversion parameters (Smoothness constraints) l = 0.5 – 0.01 l = 1.0 – 0.01 T1 T1 T2 T2 T3 T3 T4 T4 T5 T5 T6 T6

  46. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy We have to calculate differences to know where and how much the ground conditions changed Time lapse images (subsurface image at a certain moment) - Effect of inversion parameters (Smoothness constraints) l = 0.5 – 0.01 l = 1.0 – 0.01 T1 T1 T2 T2 T3 T3 T4 T4 T5 T5 T6 T6

  47. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy Time lapse difference images (subsurface changes during a certain periods) - Effect of inversion parameters (Smoothness constraints) l = 0.5 – 0.01 l = 1.0 – 0.01 T2-T1 T3-T1 T4-T1 T5-T1 T6-T1

  48. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy Time lapse difference images (subsurface changes during a certain periods) - Effect of inversion parameters (Smoothness constraints) l = 0.5 – 0.01 l = 1.0 – 0.01 T2-T1 T3-T1 T4-T1 Event still active Event almost disappeared T5-T1 T6-T1

  49. 2. DC resistivity monitoring and 4D interpretation Classical interpretation strategy Time lapse difference images (subsurface changes during a certain periods) - Effect of inversion parameters (Smoothness constraints) l = 0.5 – 0.01 l = 1.0 – 0.01 T2-T1 Which is true?? At least one guy cheating T3-T1 T4-T1 T5-T1 T6-T1

  50. 2. DC resistivity monitoring and 4D interpretation 4D interpretation strategy • From snapshots by still camera to movie by video camera • From monitoring to 4-D imaging t1 Data (d1) A 4D data set t2 Data (d2) Adopting 4Dimensional concept, incorporating the monitoring time as the 4th axis, we can establish one data set defined in the space-time domain from many data sets in the spatial domain. : : tn Data (dn) Coordinates along the 4th axis (time)

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