| 摘要(英) |
The Ilan Plain, abutting the Hsueshan range to the northwest and the Central range to the south, is a triangular alluvial delta in northeast Taiwan most likely representing the southwest end of the Okinawa Trough, a back-arc basin due to the subduction of the Philippine Sea Plate underneath the Eurasia Plate. In this study, we deployed an array of ten broadband stations since Nov. 2013. The array is roughly distributed evenly on the Ilan Plain near mountain hills, which is designed to investigate the spatial variations of Moho depths.
We conduct receiver function analysis on data of teleseismic events, mostly from the southeast quadrant. The P converted to S phase (Ps) and PpPms, PsPms+PpSms multiple reflection phases at the Moho are examined. The analysis is done by time-domain iterative deconvolution, which progressively subtracted from the radial-component seismogram with the convolution of vertical-component seismogram and updated receiver function.
Results show that stations with or without starkly contrasts of H-κ stacking can roughly be divided into those in the south and those in the north Ilan Plain. For the five stations in the south Ilan Plain (SSE, DJE, LLK, SAJ, MSE), teleseismic events from the northwest, northeast and southwest quadrants are mostly unable to resolve receiver functions with clear Ps and/or multiple reflection later phases (PpPms, PsPms+PpSms). Having examined the convergent points of those events, we conclude that Moho discontinuities beneath the Hsueshan range, the Central range inland side, and the Ilan Plain are not sharp enough to generate all phases necessary for the H-κ analysis. For the five stations in the north Ilan Plain (SJY, DTE, NCH, NCE, DHE), the convergent points of events from the four quadrants are all fallen among the aforementioned regions and, for similar reasons, unresolvable of H-κ stacking.
The only scenario with starkly contrasts of H-κ stacking to be determined is those teleseismic events to the southeast quadrant of the five stations in the south Ilan Plain. They contribute the most abundant observations with derived receiver functions consistently exhibiting arrivals of Ps and PpPms, PsPms+PpSms phases. As a result, H-κ results are able to individually determine the Moho depths convergent beneath southeast of the Ilan Plain with depths ranging from 24 to 31km and the deepest one occurred near Suao. We conclude that the Moho discontinuities to the southeast of the Ilan Plain (the Central Range shore side, offshore Suao) are sharp enough to generate all phases necessary for the H-κ analysis.
Using the average κ as determined from the five stations in south Ilan Plain, we manage to estimate the Moho depths for the five stations in the north Ilan Plain and the results range from 27 to 29 km. Although the results are subject to certain level of uncertainty, it is the optimal approach under conditions of limited data.
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| 參考文獻 |
Angelier, J., J. C. Lee, H. T. Chu, J. C. Hu, C. Y. Lu, Y. C. Chan, T. J. Lin, Y. Font, B. Deffontaines, Y. B. Tsai (2001). The Chichi earthquake, 1999, and its role in the Taiwan orogen, Earth Plant. Sci., 333, 5-21.
Angelier, J., T.Y. Chang, J. C. Hu, C. P. Chang, L. Siame, J.C. Lee, B. Deffontaines, H.T. Chu, C.Y. Lu (2008). Does extrusion occurs at both tips of the Taiwan collision belt ? Insights from active deformation studies in the Ilan Plain and Pingtung Plain regions, Tectonophysics, 466, 356-376.
Bath, M. and R. Stefansson (1966). SP conversion at the base of the crust, Annals of Geophys., 19(2), 119-130.
Hou, C. S., J. C. Hu, K. E. Ching, Y. G. Chen, C. L. Chen, L. W. Cheng, C. L. Tang, S. H. Huang, C. H. Lo (2009). The crustal deformation of the Ilan Plain acted as a westernmost extension of the Okinawa Trough, Tectonophysics, 466, 344–355.
Hsu, Y. J., S. B. Yu, M. Simons, L. C. Kuo, and H. Y. Chen (2009). Interseismic crustal deformation in the Taiwan plate boundary zone revealed by GPS observations, seismicity, and earthquake focal mechanisms, Tectonophysics, 479, 4-18.
Hu, J. C., J. Angelier, J. C. Lee, H. T. Chu, D. Byrne (1996). Kinematics of convergence, deformation and stress distribution in the Taiwan collision area: 2-D finite-element numerical modeling, Tectonophysics, 255(3-4), 243-268.
Hu, J. C., S. B. Yu, H. T. Chu, J. Angelier (2002). Transition tectonics of northern Taiwan induced by convergence and trench retreat, Geol. Soc. Am. Special Paper 358, 149-162.
Ku, C. Y. and S. K. Hsu (2009). The Neo-Tectonic Structure of the Southwestern Tip of the Okinawa Trough, Terr. Atoms. Ocean. Sci., Vol. 20, No.5, 749-759.
Langston, C.A. (1979). Structure under Mount Rainier, Washington, inferred from teleseismic body waves, J. Geophys. Res., 84(B9), 4749-4762.
Lee, J. C., J. Angelier, and H. T. Chu (1997). Polyphase history and kinematics of a complex major fault zone in the northern Taiwan mountain belt: The Lishan Fault, Tectonophysics, 274, 97-115.
Lai, K. Y., Y. G. Chen, Y. M. Wu, J. P. Avouac, Y. T. Kuo, Y. Wang, C. H. Chang and K. C. Lin (2009). The 2005 Ilan earthquake doublet and seismic crisis in northeastern Taiwan: evidence for dyke intrusion associated with on-land propagation of the Okinawa Trough, Geophys. J. Int., 179, 678-686.
Ligorria, J. P., and C. J. Ammon (1999). Iterative deconvolution and receiver-function estimation, Bull. Seismol. Soc. Am., 89(5), 1395-1400.
Lin, J. Y., J. Sibuet, C. S. Lee, S. K. Hsu, F. Klingelhoefer, Y. Auffret, P. Pelleau, J. Crozon, C. H. Lin (2009). Microseismicity and faulting in the southwestern Okinawa Trough, Tectonophysics, 466, 268–280.
Liu, C. C. (1995). The Ilan plain and the southwestward extending Okinawa Trough, J. Geol. Soc. China 38, 229-242.
Louis S. Teng (1996), Extensional collapse of the northern Taiwan mountain belt, Geology, 24, 949-952.
Phinney, R. A. (1964). Structure of the Earth’s crust from spectral behavior of long-period body waves, J. Geophys. Res., 69(14), 2997-3017.
Sibuet, J. C., B. Deffontaines, S. K. Hsu, Thareau, N. Thareau., J. L. Formal, C. S. Liu, and ACT party (1998). Okinawa Trough backarc basin: Early tectonic and magmatic evolution, J. Geophys. Res., 103(B12), 30245-30267.
Yu, S. B., H. Y. Chen, and L. C. Kuo (1997). Velocity field of GPS stations in the Taiwan area, Tectonophysics, 274, 41-59.
Zhu, L., and H. Kanamori (2000). Moho depth variation in southern California from teleseismic receiver functions, J. Geophys. Res., 105(B2), 2969-2980.
邱詠恬，2008。利用GPS觀測資料探討宜蘭平原現金地殼變形，國立台灣大學碩士論
文，共101頁。
邱詠恬，2008。由2002-2006年之GPS觀測資料探討宜蘭平原之地殼變形，經濟部中央
地質調查所特刊，第二十號，第111-124 頁。
康竹君、張翠玉、李建成、陳柔妃，2008。南沖繩海槽之最西端及梨山斷層最北端：蘭
陽平原的構造活動特性，西太平洋地質科學，第8卷，第17-42頁。
鄧屬予，1997。台灣第四紀大地構造，經濟部中央地質調查所特刊，第18號，第1-24
頁。
趙紹錚、周銘瑋、徐瑩潔，2009。宜蘭地區地質概論與土層特徵，國立宜蘭大學工程學
刊，第5期，1-16頁。
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