地震災害對於台灣一直是一件重要且不可忽視的議題，台南位於台灣的西南部，近百年來共經歷了7次因地震而造成的嚴重災害。本研究以微地動訊號，藉由單站頻譜比法(HVSR)與微地動陣列，針對台南不同地形之微地動特性及場址效應進行分析。藉由陣列資料反演了地表淺層S波相速度，並將其與共振主頻作結合以探討地層結構以及震波響應之關係。
研究中主要設置了由為期1-4個月的173個單站所組成之密集陣列，以及60個同心圓陣列覆蓋了台南的四種地形，分別為安平平原、台南台地、大灣低地及中洲台地。單站數據用於計算HVSR以獲得場址效應之共振主頻以及振幅比。陣列數據則用於計算表面波之頻散曲線及S波的速度構造。結果顯示不同地形之下之共振主頻及振幅比有著明顯的分佈特徵。台南台地及中洲台地主頻約為1-3 Hz不等，而平原及低地則以約0.2 Hz為主，顯示其厚層沉積的特性。並藉由所得之主頻與S波速度構造結合，顯示了區域地層介面之速度及深度的變化，在平原及低地區域有著較厚的沉積，並且在台南台地中心存在一上凸之淺層構造。
此外極化分析及HVSR rotation的結果顯示，微地動的方向性與地層結構及震波能量方向有著密切關係。在時間尺度下，部分測站主頻處的振幅比受到了潮汐的影響而有著明顯的改變。在大潮期間，主頻0.2 Hz處產生了較大的振幅比，我們認為這與自然活動(潮汐)所產生的微地動相關。
本研究主要提供了台南地區密集的觀測資料，以深入了解整體大台南地區之場址特性，對於區域的淺層構造有著更進一步的了解。並且本研究採用之方法具有經濟實惠、操作便捷及應用範圍廣泛等等之優勢，在其他不同地區之地質構造研究中也能有所貢獻。

This research aims to understand the site effect in the Tainan area. We analyzed the microtremor data recorded by the dense array (CK network) and triangular arrays. The single stations in the dense array are used to get the site-effect result, which is predominant frequency and amplification, and the triangular arrays are used to get the dispersion curve as the initial model for the S wave velocity at each site. We used the Horizontal-to-vertical spectral ratio (HVSR) to analyze the site effect and Herrmann’s inversion technique to get the S wave velocity, which is differential and stochastic, and the dispersion curve for inversion is made by the F-K method. On the other hand, we let the horizontal components rotate from 0 to 180 degrees every 5 to know the maximum amplification at which azimuth. Then, we compared this HVSR rotation result to the polarization result. In addition, we used the velocity structure combined with predominant frequency to calculate the depth at each station. The site-effect results show that the predominant frequency is highly connected to the four different topographies in Tainan. Still, the amplification is generally insignificant, which means that the formation velocity contrast in the Tainan area is not apparent. In long-time records, we found that the result of the site effect obtained by HVSR would be affected by natural factors. Amplification at low frequency will become more prominent during the spring tide. Time-frequency polarization analysis and HVSR rotation show that the directivity of microtremor is related to environmental conditions. In the predominant frequency <1 Hz, we can see that it is affected by tides and waves, and the directions show that most of the stations are located in the N-S and NE-SW directions.

林耕霈 (2012). 利用永久性散射體差分干涉法探討台南地區之地殼形變, 中央大學地球物理研究所學位論文.
郭炫佑 (1999). 後甲里斷層及其附近構造, 國立中央大學地球物理研究所碩士論文.
陳榮煌 (2007). 利用微地動陣列量測資料探討台南地區之淺層S波速度構造。, 國立中正大學地震研究所碩士論文.
鍾廣吉 (1979). 台南市志 卷一 土地志地理篇, 臺南市政府.
饒瑞鈞, 景國恩, 謝宗訓, 余致義, 侯進雄, 李元希, 胡植慶, 詹瑜璋, 李建成, and 洪日豪 (2003). 台南台地的地表變形與地震潛能, 經濟部中央地質調查所特刊.
Acerra, C., G. Aguacil, A. Anastasiadis, K. Atakan, R. Azzara, P.-Y. Bard, R. Basili, E. Bertrand, B. Bettig, and F. Blarel (2004). Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations measurements, processing and interpretation, European Commission–EVG1-CT-2000-00026 SESAME.
Atakan, K., A.-M. Duval, N. Theodulidis, B. Guillier, J.-L. Chatelain, P.-Y. Bard, and SESAME-Team (2004). The H/V spectral ratio technique: experimental conditions, data processing and empirical reliability assessment, in 13th World Conference on Earthquake Engineering, Vancouver, B.C., Canada.
Burjánek, J., G. Gassner-Stamm, V. Poggi, J. R. Moore, and D. Fäh (2010). Ambient vibration analysis of an unstable mountain slope, Geophysical Journal International 180 820-828.
Burjánek, J., J. R. Moore, F. X. Yugsi Molina, and D. Fäh (2012). Instrumental evidence of normal mode rock slope vibration, Geophysical Journal International 188 559-569.
Capon, J. (1969). High-resolution frequency-wavenumber spectrum analysis, Proceedings of the IEEE 57 1408-1418.
Chen, Y.-N., Y. Gung, S.-H. You, S.-H. Hung, L.-Y. Chiao, T.-Y. Huang, Y.-L. Chen, W.-T. Liang, and S. Jan (2011). Characteristics of short period secondary microseisms (SPSM) in Taiwan: The influence of shallow ocean strait on SPSM, Geophysical Research Letters 38 n/a-n/a.
Chouet, B., G. De Luca, G. Milana, P. Dawson, M. Martini, and R. Scarpa (1998). Shallow velocity structure of Stromboli volcano, Italy, derived from small-aperture array measurements of Strombolian tremor, Bulletin of the Seismological Society of America 88 653-666.
Fat-Helbary, R. E.-S., K. O. El-Faragawy, and A. Hamed (2019). Application of HVSR technique in the site effects estimation at the south of Marsa Alam city, Egypt, Journal of African Earth Sciences 154 89-100.
Field, E., and K. Jacob (1993). The theoretical response of sedimentary layers to ambient seismic noise, Geophysical research letters 20 2925-2928.
Haskell, N. A. (1960). Crustal reflection of plane SH waves, Journal of Geophysical Research 65 4147-4150.
Herrmann, R. (1991). Surface wave inversion program (from computer program in Seismology volume IV).
Horike, M. (1985). Inversion of phase velocity of long-period microtremors to the S-wave-velocity structure down to the basement in urbanized areas, Journal of Physics of the Earth 33 59-96.
Hsieh, S. (1970). Geology and gravity anomalies of the Pingtung plain, Taiwan, in Proc. Geol. Soc. China, 76-89.
Hsieh, S. (1972). Subsurface geology and gravity anomalies of the Tainan and Chungchou structures of the Coastal Plain of southwestern Taiwan, Petrol. Geol. Taiwan 10 323-338.
Kanai, K. (1962). On the spectrum of strong earthquake motions, Bulletin of the Earthquake Research Institute, University of Tokyo 40 71-90.
Kawase, H., Y. Mori, and F. Nagashima (2018). Difference of horizontal-to-vertical spectral ratios of observed earthquakes and microtremors and its application to S-wave velocity inversion based on the diffuse field concept, Earth, Planets and Space 70 1-32.
Konno, K., and T. Ohmachi (1998). Ground-motion characteristics estimated from spectral ratio between horizontal and vertical components of microtremor, Bulletin of the Seismological Society of America 88 228-241.
Lachetl, C., and P.-Y. Bard (1994). Numerical and theoretical investigations on the possibilities and limitations of Nakamura's technique, Journal of Physics of the Earth 42 377-397.
Le Béon, M., M.-H. Huang, J. Suppe, S.-T. Huang, E. Pathier, W.-J. Huang, C.-L. Chen, B. Fruneau, S. Baize, and K.-E. Ching (2017). Shallow geological structures triggered during the Mw 6.4 Meinong earthquake, southwestern Taiwan, Terrestrial, Atmospheric and Oceanic Sciences 28 663-681.
Matsushima, T., and H. Okada (1990). Determination of deep geological structures under urban areas using long-period microtremors, Butsuri Tanko (Geophysical Exploration);(Japan) 43.
Molnar, S., J. Assaf, A. Sirohey, and S. R. Adhikari (2020). Overview of local site effects and seismic microzonation mapping in Metropolitan Vancouver, British Columbia, Canada, Engineering Geology 270 105568.
Molnar, S., J. Cassidy, S. Castellaro, C. Cornou, H. Crow, J. Hunter, S. Matsushima, F. Sánchez-Sesma, and A. Yong (2018). Application of microtremor horizontal-to-vertical spectral ratio (MHVSR) analysis for site characterization: State of the art, Surveys in Geophysics 39 613-631.
Molnar, S., and J. F. Cassidy (2006). A comparison of site response techniques using weak-motion earthquakes and microtremors, Earthquake spectra 22 169-188.
Nakamura, Y. (1989). A method for dynamic characteristics estimation of subsurface using microtremor on the ground surface, Railway Technical Research Institute, Quarterly Reports 30.
Okada, H. (2003). The microtremor survey method, Geophysical Monograph Series Number 12: Society of Exploration Geophysicists.
Oubaiche, E. H., J. L. Chatelain, A. Bouguern, R. Bensalem, D. Machane, M. Hellel, F. Khaldaoui, and B. Guillier (2012). Experimental relationship between ambient vibration H/V peak amplitude and shear‐wave velocity contrast, Seismological Research Letters 83 1038-1046.
Pérez-Moreno, L. F., Q. Rodríguez-Pérez, F. R. Zúñiga, J. Horta-Rangel, M. d. l. L. Pérez-Rea, and M. A. Pérez-Lara (2021). Site response evaluation in the Trans-Mexican Volcanic Belt based on HVSR from ambient noise and regional seismicity, Applied Sciences 11 6126.
Picozzi, M., A. Strollo, S. Parolai, E. Durukal, O. Özel, S. Karabulut, J. Zschau, and M. Erdik (2009). Site characterization by seismic noise in Istanbul, Turkey, Soil Dynamics and Earthquake Engineering 29 469-482.
Satoh, T., H. Kawase, T. Iwata, S. Higashi, T. Sato, K. Irikura, and H.-C. Huang (2001b). S-wave velocity structure of the Taichung basin, Taiwan, estimated from array and single-station records of microtremors, Bulletin of the seismological Society of America 91 1267-1282.
Satoh, T., H. Kawase, and S. i. Matsushima (2001a). Estimation of S-wave velocity structures in and around the Sendai basin, Japan, using array records of microtremors, Bulletin of the seismological society of America 91 206-218.
Socco, L., and C. Strobbia (2004). Surface‐wave method for near‐surface characterization: A tutorial, Near surface geophysics 2 165-185.
Stanko, D., S. Markušić, S. Strelec, and M. Gazdek (2017). HVSR analysis of seismic site effects and soil-structure resonance in Varaždin city (North Croatia), Soil Dynamics and Earthquake Engineering 92 666-677.
Toshinawa, T., J. J. Taber, and J. B. Berrill (1997). Distribution of ground-motion intensity inferred from questionnaire survey, earthquake recordings, and microtremor measurements—A case study in Christchurch, New Zealand, during the 1994 Arthurs Pass earthquake, Bulletin of the Seismological society of America 87 356-369.
Vidale, J. E. (1986). Complex polarization analysis of particle motion, Bulletin of the Seismological society of America 76 1393-1405.
Wu, C. F., and H. C. Huang (2013). Near‐Surface Shear‐Wave Velocity Structure of the Chiayi Area, Taiwan, Bulletin of the Seismological Society of America 103 1154-1164.