地震波可視為震源、波傳路徑與測站﹙場址效應﹚等三大參數所組成。其中震源參數包括地震規模、震源時間函數、震源機制與地震矩等項目，這些都是瞭解地震破裂物理行為的重要依據。傳統上，評估斷層整體的破裂行為，主要利用不同方位角測站所觀測的震源歷時，藉由破裂方向性分析斷層的破裂長度、破裂速度、平均震源歷時等；而震源機制普遍採用地震矩張量逆推法推算，但其基本假設須將各測站的震源時間函數視為同一定值，忽略破裂方向的影響。在本研究中，我們依據遠場震波理論發展出一套新方法，可同步計算震源破裂方向性及震源機制。其過程可分成下列步驟：第一步驟透過簡易的逆推技巧搜尋可能的震源時間函數，即可單獨求得每個測站的最佳震源時間函數與擬輻射模式﹙pseudo radiation pattern﹚；第二步驟利用蒙地卡羅法搜尋斷層的走向、傾角及滑移角度，以最小平方法為基礎，比較各測站的擬輻射模式與理論輻射模式求算最佳震源機制與地震矩；第三步驟根據有限震源理論﹙finite source theory﹚，由不同方位角之震源時間函數變化推算震源破裂方向性。將本法應用於4個全球與1個台灣地區之中大規模地震﹙1992 Landers、1994 Northridge、2004 Iran、2005 Miyagi-Oki、1999嘉義地震﹚，分析結果與前人研究相當吻合，顯示本法確可有效同步計算各項地震斷層參數。歸納主要結論如下：第一、利用訊噪比可有效篩選測站，以輔助人工辨識初達 波之不確定性；第二、震源機制為準確且相對穩定的因子，利用單一 波波相即可求得穩定信賴的結果；第三、本研究可明確決定屬於走向斷層的1992年Landers地震的最佳破裂面，其餘4個逆衝斷層則較難決定；第四、所決定的斷層長度及平均震源歷時一般隨地震矩增加而增加，透過本研究可有效決定中規模地震的斷層參數，對決定震源尺度律﹙source scaling law﹚有重大的幫助，可藉此了解中、大規模地震間物理行為的異同。未來本研究努力的方向，將著重於發展半自動系統，以便應用於主要地震斷層參數的快速求算，並作為各種震源研究、地動預估及地震災害評估的分析基礎，若能更進一步搭配適當的區域速度模型與即時傳輸的強地動資料，相信將可為台灣地區的地震預防與減災工作提供參考。

For systemically estimation of the fault parameters and rupture directivity, we developed a new algorithm for the simultaneous determination of the earthquake source parameters, including seismic moment, focal mechanism, rupture length and rupture velocity, using far-field waveforms. The observed waveforms are corrected for instrument response, geometrical spreading and surface effects. The focal mechanism of an earthquake was determined through a grid search, while the pseudo radiation patterns of -wave were obtained for each station. The best solution for the focal mechanism was determined by comparing the pseudo and theoretical radiation patterns for every step on grid search. The source time functions obtained from the stations are, furthermore, to be used to estimate the rupture length and rupture velocity accounted for rupture directivity.
We applied this method to four moderate to large global earthquakes for Mw5.8-7.3. A moderate Taiwan earthquake is also analyzed to demonstrate the possibility of rapidly simultaneous determination on the finite fault source parameters for local earthquake. The estimated fault parameters and rupture directivity for the five earthquakes are quite consistent with those obtained by previous studies. For the 1992 Landers earthquake, which had a strike-slip mechanism, the rupture plane was clearly determined from the developed algorithm. For other events with thrust mechanism, it is difficult to determine the rupture plane, but other fault parameters were determined robustly, especially on focal mechanism. The rupture lengths and source durations of the five earthquakes have positive correlation to the seismic moment. In this study, a promising approach to determine the focal mechanism, seismic moment and rupture length of an earthquake was presented. Future efforts related to this work will focus on developing a semi-automatic data process based on the method to quickly estimate the source parameters. Further studies on this work can also provide important information on scaling of the earthquakes for better understanding of earthquake physics on rupture characteristics. Moreover, on purpose of seismic hazard assessment, this method will be efficiently applied to regional earthquakes on account of proper local velocity structure model and real-time data transmission.

Aki, K., 1967. Scaling law of seismic spectrum, J. Geophys. Res., 72, 1217-1231.
Aki, K. and P. G. Richards, 2002. Quantitative Seismolog﹙Second Edition﹚, University Science Books, Sausalito CA, 700pp.
Ammon, C. J., A. A. Velasco, and T. Lay, 1993. Rapid estimation of rupture directivity: Application to the 1992 Landers ﹙Ms=7.4﹚ and Cape Mendocino ﹙Ms=7.2﹚, Califorina earthquake, Geophys. Res. Lett., 20, 97-100.
Ben-Menahem, A., 1961. Radiation of seismic surface-waves from finite moving sources, Bull. Seism. Soc. Am., 51, 401-435.
Bollinger, G. A., 1968. Determination of earthquake fault parameters from long-period P waves, J. Geophys. Res., 73, 785-807.
Bollinger, G. A., 1970. Fault length and fracture velocity for the Kyushu, Japan, earthquake of October 3, 1963, J. Geophys. Res., 75, 955-964.
Bullen, K. E. and B. A. Bolt, 1985. An Introduction to the Theory of Seismology, 4th edn, Cambridge University Press, Cambridge, 499pp.
Cassidy, J. F., 1995. Rupture directivity and slip distribution for the Ms 6.8 earthquake of 6 April 1992, offshore British Columbia: An application of the empirical Green’s function method using surface waves, Bull. Seism. Soc. Am., 85, 736-746.
Chang, J. P., R. D. Hwang and C. Y. Wang, 2006. Analysis of rupture directivity for the 2004 Sumatra earthquake from Rayleigh-wave phase velocity, Earth Planets Space.﹙submitted﹚
Chapman, C.H., 1978. A new method for computing synthetic seismograms, Geophys. J. R. Astr. Soc., 56, 81-85.
Christensen, D. H. and L. J. Ruff, 1986. Rupture process of the March 3, 1986 Chilean earthquake, Geophys. Res. Lett., 13, 721-724.
Chung, W.-Y. and H. Kanamori, 1980. Variation of seismic source parameters and stress drops within a descending slab and its implications in plate mechanics, Phys. Earth Planet. Inter., 23, 134-159.
Cohee, B. P. and G. C. Beroza, 1994. Slip Distribution of the 1992 Landers Earthquake and Its Implications for Earthquake Source Mechanics, Bull. Seism. Soc. Am., 84, 692-712.
Dreger, D. S., 1994. Investigation of the Rupture Process of the 28 June 1992 Landers Earthquake Utilizing TERRAscope, Bull. Seism. Soc. Am., 84, 713-724.
Filson, J. and T. V. McEvilly, 1967. Love spectra and the mechanism of the 1966 Parkfield sequence, Bull. Seism. Soc. Am., 57, 1245-1257.
Fuchs, K. and Muller, G., 1971. Computation of synthetic seismograms with the reflectivity method and comparison with observations, Geophys. J. R. Astr. Soc., 23, 417-433.
Furumoto, M and I. Nakanishi, 1983. Source times and scaling relations of large earthquakes, J. Geophys. Res., 88, 2191-2198.
Gibowicz, S. J., 1986. Physics of fracturing and seismic energy release: A review, PAGEOPH, 124, 611-658.
Hanks, T. C. and M. Wyss, 1972. The use of body-wave spectra in the determination of seismic-source parameters, Bull. Seism. Soc. Am., 62, 561-589.
Hanks, T. C. and W. Thatcher, 1972. A graphical representation of seismic source parameters, J. Geophys. Res., 77, 4393-4405.
Hanks, T. C. and H. Kanamori, 1979. A moment magnitude scale, J. Geophys. Res., 84, 2348-2350.
Hartzell, S., 1978. Earthquake aftershocks as Green’s functions, Geophys. Res. Lett., 5, 1-4.
Hartzell, S. H. and T. H. Heaton, 1985. Teleseismic time function for large, shallow subduction zone earthquake, Bull. Seism. Soc. Am., 75, 965-1004.
Haskell, N., 1969. Elastic displacements in the near-field of a propagating fault, Bull. Seism. Soc. Am., 59, 865-908.
Helmberger, D.V., 1968. The crust-mantle transition in the Bering Sea,Bull. seism. Soc. Am., 58, 179-214.
Houston, H. and H. Kanamori, 1986. Source spectra of great earthquakes: teleseismic constraints on rupture process and strong motion, Bull. Seism. Soc. Am., 76, 19-42.
Hudnut, K. W., Z. Shen, M. Murray, S. McClusky, R. King, T. Herring, B. Hager, Y. Feng, P. Fang, A. Donnellan, and Y. Bock, 1996. Co-seismic Displacement of the 1994 Northridge, California, Earthquake, Bull. Seism. Soc. Am., 86, S19-S36.
Hwang, R. D., G. K. Yu, and J. H. Wang, 2001. Rupture directivity and source-process time of the September 20, 1999 Chi-Chi, Taiwan, earthquake estimated from Rayleigh-wave phase velocity, Earth Planets Space, 53, 1171-1176.
Kanamori, H. and J. J. Cipar, 1974. Focal process of the great Chilean earthquake May 22, 1960, Phys. Earth Planet. Inter., 9, 128-136.
Kanamori, H. and D. L. Anderson, 1975. Theoretical basis of some empirical relations in seismology, Bull. Seism. Soc. Am., 65, 1073-1095.
Kanamori, H. and G. Stewart, 1976. Mode of the strain release along the Gibbs fracture zone, Mid-Atlantic ridge, Phys. Earth Planet. Inter., 11, 312-332.
Kennett, B. L. N. and E. R. Engdahl, 1991. Traveltimes for global earthquake location and phase identification, Geophys. J. Int., 105, 429-465.
Kennett, B. L. N., E. R. Engdahl, and R. Buland, 1995. Constraints on seismic velocities in the Earth from travel times, Geophys J Int, 122, 108-124.
Khattri, K. N., 1969. Determination of earthquake fault plane, fault area and rupture velocity from the spectra of long period P waves and the amplitude of SH waves, Bull. Seism. Soc. Am., 59, 615-630.
Kikuchi, M. and M. Ishida, 1993. Source retrieval for deep local earthquakes with broadband records, Bull. Seism. Soc. Am., 83, 1855-1870.
Langston, C.A. and D. V. Helmberger, 1975. A procedure for modeling shallow dislocation sources, Geophys. J., 42, 117-130.
Lay, T. and T. C. Wallace, 1995. Modern Global Seismology, Academic Press, San Diego, California, 521pp.
Lazarte, C. A., J. D. Bray, A. M. Johnson, and R. E. Lemmer, 1994. Surface Breakage of the 1992 Landers Earthquake and Its Effects on Structures, Bull. Seism. Soc. Am., 84, 547-561.
Ma. K.-F. and J. Mori, 1998. Rupture process of the June 25, I-Lan earthquake, Symposium on Taiwan Strong Motion Instrumentation Program ﹙III﹚, 141-143.
Ma, K.-F., J. Mori, S.-J. Lee, and S.-B. Yu, 2001. Spatial and temporal distribution of slip for the 1999 Chi-Chi, Taiwan, earthquake, Bull. Seism. Soc. Am., 91, 1069-1087.
Nakanishi, I., 1991. Source process of the 1989 Sanriku-Oki earthquake, Japan: Source function determined using empirical green function, J. Phys. Earth., 39, 661-667.
Okal, E. A., 1992. A student’s guide to teleseismic body wave amplitude, Seism. Res. Lett., 63, 169-180.
Pegler, G. and S. Das, 1996. Analysis of the relationship between seismic moment and fault length for large crustal strike-slip earthquakes between 1977-92, Geophys. Res. Lett., 23, 905-908.
Reid, H. F., 1910. The mechanics of the earthquake, The California Earthquake of April 18, 1906, Report of the State Investigation Commission, Vol.2, Carnegie Institution of Washington, Washington, D.C., P.16-28.
Romanowicz, B., 1992. Strike-slip earthquakes on quasi-vertical transcurrent faults: inferences for general scaling relations, Geophys. Res. Lett., 19, 481-484.
Romanowicz, B. abd J. B. Rundle, 1993. On scaling relations for large earthquakes, Bull. Seism. Soc. Am., 83, 1294-1297, 65-70.
Ruff, L. and H. Kanamori, 1983. The rupture process and asperity distribution of three great earthquakes from long-period diffracted P-wave, Phys. Earth Planet. Inter.,31, 202-230.
Scholz, C. H., 1982. Scaling laws for large earthquakes: consequences for physical models, Bull. Seism. Soc. Am., 72, 1-14.
Scholz, C. H., 1994. A reappraisal of large earthquake scaling, Bull. Seism. Soc. Am., 84, 215-218.
Scholz, C. H., 1997. Size distributions for large and small earthquakes, Bull. Seism. Soc. Am., 87, 1074-1077.
Scholz, C. H., C. Aviles, and S. Wesnousky, 1986. Scaling differences between large intraplate and interplate earthquakes, Bull. Seism. Soc. Am., 76, 65-70.
Singh, S. K., J. Pacheco, M. Ordaz, and V. Kostoglodov, 2000. Source time function and duration of Mexican earthquakes, Bull. Seism. Soc. Am., 90, 468-482.
Stein, S. and M. Wysession, 2003. An Introduction to Seismology, Earthquake, and Earth Structure, Blackwell Publishing, UK, 498pp.
Thatcher, W. and T. C. Hanks, 1973. Source parameters of southern California earthquakes, J. Geophys. Res., 78, 8547-8576.
Thio, H. K. and H. Kanamori, 1996. Source complexity of the 1994 Northridge earthquake and its relation to aftershock mechanisms, Bull. Seism. Soc. Am., 86, S84-S92.
Tsai, C.-C. P., 1997. Relationships of seismic source scaling in the Taiwan region, TAO, 8, 49-68.
Unruh, J. R., W. R. Lettis, and J. M. Sowers, 1994. Kinematic Interpretation of the 1992 Landers Earthquake, Bull. Seism. Soc. Am., 84, 537-546.
Vassiliou, M. S. and H. Kanamori, 1982. The energy release in earthquakes, Bull. Seism. Soc. Am., 72, 371-387.
Velasco, A. A., C. J. Ammon, and T. Lay, 1994. Empirical green function deconvolution of broadband surface waves: Rupture directivity of the 1992 Landers, California ﹙Mw=7.3﹚, earthquake, Bull. Seism. Soc. Am., 84, 735-750.
Wald, J. D. and T. H. Heaton, 1994. Spatial and Temporal Distribution of Slip for the 1992 Landers, California, Earthquake, Bull. Seism. Soc. Am., 84, 668-691.
Wald, J. D., T. H. Heaton, and K. W. Hudunt, 1996. The slip history of the 1994 Northridge, California, Earthquake determined from strong-motion, teleseismic, GPS, and leveling data, Bull. Seism. Soc. Am., 86, S49-S70.
Wang, J.-H. and S. S. Ou, 1998. On scaling of earthquake faults, Bull. Seism. Soc. Am., 88, 758-766.
Yagi, Y., 2005. Preliminary Results of Rupture Process for August 16 2005 Miyagi-Oki, Japan, earthquake. Posted on http://www.geo.tsuk uba.ac.jp/ press_HP/yagi/EQ/20050816NorthJapan.
Yoshida, S., 1988. Waveform inversion for rupture processes of two deep earthquakes in the Izu-Bonin region, Phys. Earth Planet. Inter., 52, 85-101.
Zhang, J. and H. Kanamori, 1988. Source finiteness of large earthquakes measured from long-period Rayleigh waves, Phys. Earth. Planet. Inter., 52, 56-84.
Incorporated Research Institution for Seismology Data Management System, 1994. Federation of Digital Seismograph Networks Station Book – Appendix B：Response curves for FDSN stations.
高弘，簡珮如，郭鎧紋，鄭文彬，2000. 以台灣寬頻地震網及強震波形資料合併反演地震震源參數, 中央氣象局地震技術報告彙編, 第24卷, 103-115.
吳相儀，2000. 台灣地區中大型地震震源參數分析，國立中央大學地球物理研究所碩士論文，台灣中壢，119頁。
張建興，2004. 高密度地震資料分析及其用於台灣中部及東部孕震構造之研究，國立中央大學地球物理研究所博士論文，台灣中壢，156頁。