Title Page
ABSTRACT
국문 초록
Contents
NOMENCLATURE 13
CHAPTER 1. INTRODUCTION 17
1.1. Previous Studies 19
1.2. Geological Settings 20
CHAPTER 2. Methods 22
2.1. Data Processing and Phase Velocity Picking 22
2.2. The Effect of Transient Volcanic Signal on RCS 28
2.3. Eikonal Tomography 30
2.4. Azimuthal Anisotropy 33
CHAPTER 3. Synthetic Resolution Test 35
3.1. Checkerboard Test for Velocity Anomalies 35
CHAPTER 4. Result 40
4.1. Tomography 40
4.2. Azimuthal Anisotropy 43
CHAPTER 5. Discussion 46
5.1. Tomography Result Correlation with the Geology 46
5.2. Tomography Result Correlation with the Topography 51
5.3. Azimuthal Anisotropy 53
CHAPTER 6. Conclusion 57
REFERENCES 59
Figure 1. Geological Settings of southern Korean Peninsula 20
Figure 2. Station distribution of Southern Korean accelerometer network KMA stations (Red triangle) and KIGAM stations (Blue circle) 22
Figure 3. Histogram of Distance to Nearest Station 23
Figure 4. Average computation time difference between CPU (Blue) and GPU (Red) 24
Figure 5. RCS between the station KS.BGDB and KS.CSDB 26
Figure 6. Reference curve (Blue) and picked phase velocity curve (Red) 26
Figure 7. Picked phase velocity curve (Blue) and cubic spline fitted line (Red) 27
Figure 8. Mean dispersion curve of all pairs (Blue) and its standard deviation (Red) 27
Figure 9. EGF and RCS between KG.KNUD and KS.JKJA stations a) raw EGF, b) raw RCS, c) acausal part of EGF, d) RCS Fourier transformed from c),... 29
Figure 10. Phase velocity measurement from KS.ANMA station at 0.25 Hz a) multiquadric, b) cubic, c) quintic method is used. 32
Figure 11. An example of azimuthal anisotropy fitting at 128.33 E, 35.70 N Mean velocity(C0) 2.96km/s, amplitude(A) 3.93%, and azimuth(φ) 87.8 degrees 34
Figure 12. Checkerboard test on 0.25 Hz, 0.5 Hz, 0.75 Hz, 1.0 Hz with a size of checkerboard of 25 km, 30 km, 40 km by using cubic RBF 36
Figure 13. Checkerboard test on 0.25 Hz, 0.5 Hz, 0.75 Hz, 1.0 Hz with a size of checkerboard of 50 km, 100 km, 200 km by using cubic RBF 37
Figure 14. An example of cross-section through 128°E, with different checker size 38
Figure 15. An example of cross-section through 128°E, with different checker size 39
Figure 16. Eikonal Tomography Result of southern Korean Peninsula 40
Figure 17. Phase Velocity Uncertainty Results of southern Korean Peninsula 42
Figure 18. Uncertainty values of every grid points. Mean value is plotted as black line, and its standard deviation is plotted as red lines. 43
Figure 19. Azimuthal anisotropy Results of southern Korean Peninsula 44
Figure 20. 0.75 Hz tomography and the distribution of volcanic and sedimentary rocks in the southern part of the Korean Peninsula. 46
Figure 21. 1.0 Hz tomography of Gyeongsang Basin and nearby area 47
Figure 22. Sensitivity kernel of Rayleigh wave phase velocity at 0.2 to 1.0 Hz based on 1-D structure from Kim et al. 2011 48
Figure 23. 1.0 Hz tomography of Yeonil Basin and nearby area 49
Figure 24. Topography (left), tomography (middle), and gradient of topography (right) The tomography is conducted in 1.0 Hz,... 52
Figure 25. 0.75 Hz tomography with topography higher than 600m 52
Figure 26. Azimuthal anisotropy of the Gyeongsang Basin observed at 1.0 Hz 55