Title Page
Contents
ABSTRACT 12
Chapter 1. Introduction 14
1.1. Background 14
1.2. Previous researches on hydroseismology 21
1.2.1. Monitoring networks and observations 22
1.2.2. Pre-seismic groundwater change 25
1.2.3. Mechanisms for co-seismic changes 26
1.2.4. Appropriate monitoring conditions 29
1.3. Objectives 31
1.4. Data acquisition 33
Chapter 2. Methodology 36
2.1. Overall approach of this study 36
2.2. Previously suggested methods to screen the earthquake effects 38
2.3. Developing a method to identify groundwater changes by earthquake 42
2.3.1. Developing a method to screen the earthquake effects 42
2.3.2. Validation of the method 49
2.3.3. Advantages and limitations 51
Chapter 3. Result and discussion 56
3.1. Application of the developed method 56
3.2. Groundwater changes due to the domestic earthquakes 58
3.2.1. The 2007 Odaesan earthquake 58
3.2.2. The 2008 Gongju earthquake 70
3.3. Groundwater changes due to the distant earthquakes 74
3.3.1. The 2008 Wenchuan earthquake 74
3.3.2. The 2011 Tohoku-Oki earthquake 91
3.4. Controlling factors for groundwater responses to earthquakes 110
3.4.1. Factors controlling groundwater responses 110
3.4.2. Distances from epicenter and magnitude of earthquakes 111
3.4.3. Transmissivity and bedrock types 115
3.5. Interpretation of the direction, type, and duration of the changes 121
Chapter 4. Conclusion 125
4.1. Summary and implications 125
4.2. Summary for the future study 130
Appendices 133
Appendix A. Groundwater changes due to Tohoku-Oki earthquake 134
Appendix B. Figures for commonly responded wells and their locations. 168
References 175
국문요약 186
Table 1-1. Summary of mechanisms that load to fluctuations in groudwater levels (Freeze and Cherry, 1979). 18
Table 1-2. Precision and resolution of data logger installed in the NGMS. 34
Table 2-1. Previously suggested methods to identify seismic effects on groundwater. 41
Table 2-2. The properties of the developed method in this study. 51
Table 3-1. List of the stations showing changes by Odaesan EQ. 62
Table 3-2. List of large earthquakes occurred near Korean Peninsula in May 2008. 76
Table 3-3. List of stations showing water-level and changes by Wenchuan earthquake. 77
Table 3-4. Stations with water-level changes influenced by the M9.0 Tohoku-Oki earthquake. 94
Table 3-5. Wells showing changes in Temperatures and EC responding to Tohoku-Oki earthquake. 96
Table 3-6. List of large earthquakes occurred within 2 degrees distance of the epicenter of Tohoku-Oki earthquake in March 2011. 107
Table 3-7. Wells responded in common to Wenchuan and Tohoku-Oki earthquakes. 109
Table 4-1. A sample matrix for interpreting the changes in aquifer system. 132
Figure 1-1. Water-level change by 2008 Wenchuan earthquake at Gwangneung station. 19
Figure 1-2. Location of observatories of the National Groundwater Monitoring System of Korea. 35
Figure 2-1. Overall approach of this study. 37
Figure 2-2. Flow chart of data analysis using the developed method. 45
Figure 2-3. Results of spectral analysis for (a) Seosan-Palbong (located in western coastal area), (b) Goesan-Goesan (located in inland), and (c) Donghae-Guiwoon stations (located in eastern coastal area). 48
Figure 2-4. Water-level fluctuations in wells responded to Wenchuan earthquakes 50
Figure 2-5. Examples of masking effects on water-level: (a) Geochang-Shinwon and (b) Chilgok-Gasan stations. 55
Figure 3-1. The epicenter (black star) and location of wells (colored circle) which showed water-level changes. 59
Figure 3-2. Schematic diagram of spectral analysis using MATLAB7.0./4 with data of station Cheongdo-Cheongdo. 61
Figure 3-3. Temporal variation of water level (above) and the result of spectral analysis (below) 63
Figure 3-4. Location map for 2008 Gongju earthquake and NGMS station in Gongju city area. 70
Figure 3-5. Water-level fluctuation at Gongju-Banpo station during (a) whole studied period of 1 month and (b) the first 20 days. 72
Figure 3-6. Water-level and EC fluctuation at Gongju-Banpo station. 73
Figure 3-7. Location of the monitoring well responded to Wenchuan earthquake. 75
Figure 3-8. Water-level fluctuation during the analysis period (above) and applied windows to 24-hr water-level changes (below) 86
Figure 3-9. Fluctuations curve on electric conductivity of (a) Andong-Giran and (b) Pyeongchang-Daehwa stations. 89
Figure 3-10. Location of wells responded to 2011 M9.0 Tohoku-Oki earthquake. 93
Figure 3-11. Groundwater responses to 2011 Tohoku-Oki earthquake 102
Figure 3-12. Types of water-level changes 105
Figure 3-13. Effects of successive earthquakes observed at (a) Eumseong-Daeso, (b) Hwaseong-Yanggam, and (c) Yangju-Gwangjeock stations. 108
Figure 3-14. Magnitude of water-level changed to the distance from epicenter. 114
Figure 3-15. Water-level changes vs.transmissivity for (a) Odaesan, (b) Wenchuan, and (c) Tohoku-Oki earthquakes. 117
Figure 3-16. Water-level changes in absolute values and transmissivities of the aquifer at the monitoring stations for Wenchuan and Tohoku-Oki earthquakes. 118
Figure 3-17. Examples for direction of changes: (a) rise, and (b) drop. 122
Figure 3-18. Examples for type of changes: (a) gradual, (b) peak-like, and (c) step-like types. 123
Figure 3-19. Examples for duration of changes: (a) recovery, and (b) no recovery. 124