臺灣博碩士論文加值系統

非火山長微震 (Non-volcanic tremor, NVT) 為常見於世界上主要板塊邊界之特殊地震訊號。其特徵為︰(1)持續時間長，可從數分鐘至數十分鐘；(2)振幅微弱；(3)無明顯體波波相；(4)主頻介於1-10 Hz之間。由於人工辨識長微震困難度高，傳統地震學利用S-P波走時差之定位方式難以適用，因此許多專為長微震設計的偵測方法紛紛被提出。長微震依形成機制可分為觸發型長微震(triggered tremor)以及自發型長微震(ambient tremor)。觸發型長微震多由遠震表面波所觸發；自發型長微震則被解釋成與流體存在有關，或是板塊交界面上剪力滑動所造成。台灣過去曾於1998-2010年間對觸發型長微震進行系統性的搜尋，並發現數個由遠震表面波所觸發的長微震事件 (Peng and Chao, 2008；葉庭禎, 2011；Chao et al., 2012)。然而對於自發型長微震之研究仍相當缺乏，其發生位置、時間特徵、發震機制仍未有充分討論。本研究針對台灣中央山脈南段之自發型長微震，設計半自動化偵測系統，分別針對(1)不同測站具一致波形；(2)振幅大於背景雜訊；(3)持續時間夠長，設計三階段的門檻篩選，並利用此〝似長微震目錄〞進行人工判識。分析2009-2010年間連續資料，結果共定義121個明顯的自發型長微震事件，持續時間由5至30分鐘不等。其震源位於中央山脈南段孕震帶以下，深度多集中於16-34 km間，水平空間跨距約23 km × 55.5 km。分析長微震之累積持續時間，我們發現長微震活動度於2個區域M>6.0地震發生後明顯變高，但此現象無法以簡單的靜態庫倫應力改變來解釋。我們亦比較觸發型與自發型長微震之時空分布與訊號特徵，結果顯示觸發型長微震與自發型長微震之頻譜曲線類似，且振幅與持續時間關係均遵循指數關係，因此可對應至類似的震源過程。

In a transition zone between stable sliding and locked faults, occurrence of noise-like, non-volcanic tremors (NVT) are found to play an important role in full spectrum of strain release processes. The triggered and ambient tremor episodes previously discovered in Taiwan illustrates the generation potential of non-volcanic tremors underneath Central Range. However, small tremor bursts (several to tens of minutes) with high noise level and spare seismic station coverage makes the automatic detection in this region problematic and challenging. We propose an automatic detection scheme to identify tremors in this particular region. Applying this detection method in the two years data starting from January, 2009, we found 121 ambient tremor episodes with duration ranging from 5 to 30 minutes. The detected tremor events are confined in a small area of 23 x 55.5 km2 with the depth range of 16-34 km. We also obs
erve larger number of tremors at the time of two local M6 earthquakes. Such acceleration lasted 70 and 90 days after the mainshocks. Given the uncertainty of assumed tremor source model, the static stress triggering relationship between M6 event and tremor is inconclusive. The scaling relationship between the duration and amplitude of ambient tremors fits an exponential model, suggesting a scale-bound source process.

中文摘要............................................. I
Abstract........................................... II
致謝................................................ III
目錄................................................ IV
圖目錄.............................................. VIII
表目錄.............................................. X

第一章 研究動機...................................... 1
第二章 前人研究...................................... 2
2.1 非火山長微震簡介............................. 2
2.1.1 波形特徵.................................. 2
2.1.2 持續時間特徵............................... 2
2.1.3 振幅與持續時間關係.......................... 6
2.1.4 頻率特徵.................................. 7
2.1.5 震源深度與機制............................. 8
2.2 非火山長微震偵測方法............................ 10
2.2.1 Suda et al. (2009)...................... 10
2.2.2 Nadeau and Guilhem (2009)............... 11
2.2.3 Kao et al. (2007)....................... 11
2.2.4 Wech et al. (2008)...................... 13
2.2.5 Walter et al. (2011).................... 14
2.3 非火山長微震與慢滑移(Slow-slip)事件之關係......... 16
2.4 非火山長微震過去在台灣的研究...................... 19
2.5 本研究欲解決之問題.............................. 20
第三章 研究方法...................................... 21
3.1 研究區域與測站選定.............................. 21
3.2 連續紀錄資料之處理.............................. 23
3.3 品質不佳資料之排除.............................. 24
3.4 自動化偵測之流程................................ 24
3.4.1 第一階段—波形相似度檢驗...................... 26
3.4.2 第二階段—平均訊噪比檢驗...................... 35
3.4.3 第三階段—持續時間檢驗........................ 41
3.4.4 自動化偵測與目視辨認之比較.................... 43
3.5 長微震事件之定位................................ 46
3.5.1 定位原理、權重與不確定性估計.................. 46
3.5.2 定位之資料前處理............................ 47
3.5.3 速度模型................................... 48
3.5.4 格點搜尋範圍及格點密度........................ 50
第四章 研究結果....................................... 51
4.1 偵測結果....................................... 51
4.2 自發型長微震訊號特徵............................. 53
4.2.1 長微震訊號之時頻特徵......................... 53
4.2.2 長微震之持續時間特徵......................... 55
4.2.3 長微震之發震時間............................ 57
4.3 自發型長微震空間分布............................. 58
4.4 自發型長微震時間分布............................. 60
第五章 討論.......................................... 64
5.1長微震震源區之地質特性............................ 64
5.1.1 應力環境與地震型態........................... 65
5.1.2 地磁異常................................... 68
5.1.3 地電阻異常................................. 69
5.1.4 地熱環境與Q值研究........................... 69
5.2長微震與大地震之觸發關係........................... 73
5.3長微震與背景地震活動度之關係........................ 75
5.4觸發與自發型長微震之比較........................... 76
5.4.1 時間分布................................... 76
5.4.2 空間分布................................... 78
5.4.3 頻率內涵................................... 79
5.4.4 振幅-持續時間關係............................ 80
附錄一 長微震目錄...................................... 83
參考文獻............................................. 87

Aki, K., and R. Y. Koyanagi (1981), Deep volcanic tremor and magma ascent mechanism under Kilauea, Hawaii, J. Geophys. Res., 86, 7095 –7109.
Aki, K., and P. G. Richards, Quantitative Seismology, 2nd Edition, University Science Books, Sausalito, 2002.
Audet, P., Bostock, M. G., Christensen, N. I., and Peacock, S. M. (2009). Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing. Nature, 457(7225), 76-78.
Becken, M., Ritter, O., Bedrosian, P. A., and Weckmann, U. (2011). Correlation between deep fluids, tremor and creep along the central san andreas fault. Nature, 480(7375), 87-90.
Benoit, J. P., McNutt, S. R., and Barboza, V. (2003). Duration-amplitude distribution of volcanic tremor. J.Geophys.Res., 108, 2146.
Beroza, G. C., and Ide, S. (2011). Slow earthquakes and nonvolcanic tremor. Annual Review of Earth and Planetary Sciences, 39(1), 271-296.
Bertrand, E. A., Unsworth, M. J., Chiang, C., Chen, C., Chen, C., Wu, F. T., et al. (2012). Magnetotelluric imaging beneath the taiwan orogen: An arc-continent collision. J.Geophys.Res., 117, B01402.
Brown, K. M., Tryon, M. D., DeShon, H. R., Dorman, L. M., and Schwartz, S. Y. (2005). Correlated transient fluid pulsing and seismic tremor in the costa rica subduction zone. Earth and Planetary Science Letters, 238(1–2), 189-203.
Chao, K., Peng, Z., Wu, C., Tang, C., and Lin, C. (2012). Remote triggering of non-volcanic tremor around taiwan. Geophysical Journal International, 188(1), 301-324.
Chi, W., and Reed, D. L. (2008). Evolution of shallow, crustal thermal structure from subduction to collision: An example from taiwan. Geological Society of America Bulletin, 120(5-6), 679-690.
Chiang, C. W., C. C. Chen, M. J. Unsworth, E. A. Bertrand, C. S. Chen,T. D. Kieu, and H. L. Hsu (2010), The deep electrical structure of southern Taiwan and its tectonic implications, Terr. Atmos. Ocean. Sci., Vol. 21, No. 6, 879-895.
Dragert, H., Wang, K., and James, T. S. (2001). A silent slip event on the deeper cascadia subduction interface. Science, 292(5521), 1525-1528.
Gallego, A. (2010). Non volcanic tremors and seismic noise tomography at the chile triple junction. (Doctoral dissertation, University of Florida). Dissertation Abstracts International, 72-05
Gomberg, J., Rubinstein, J. L., Peng, Z., Creager, K. C., Vidale, J. E., and Bodin, P. (2008). Widespread triggering of nonvolcanic tremor in california. Science, 319(5860), 173-173.
Gutenberg, B., and C. F. Richter (1954), Magnitude and energy of earthquakes, Ann. Geofis., 9, 1 – 15.
Gürer, A., and Bayrak, M. (2007). Relation between electrical resistivity and earthquake generation in the crust of west anatolia, turkey. Tectonophysics, 445(1), 49-65.
Hacker, B. R., Peacock, S. M., Abers, G. A., and Holloway, S. D. (2003). Subduction factory 2. are intermediate-depth earthquakes in subducting slabs linked to metamorphic dehydration reactions? J.Geophys.Res., 108, 2030.
Hanks, T. C., and Kanamori, H. (1979). A moment magnitude scale. J.Geophys.Res., 84, 2348-2350.
Hirose, H., and Obara, K. (2006). Short-term slow slip and correlated tremor episodes in the tokai region, central japan. Geophysical Research Letters, 33(17), L17311.
Hsu, Y., Rivera, L., Wu, Y., Chang, C., and Kanamori, H. (2010). Spatial heterogeneity of tectonic stress and friction in the crust: New evidence from earthquake focal mechanisms in taiwan. Geophysical Journal International, 182(1), 329-342.
Ide, S., Beroza, G. C., Shelly, D. R., and Uchide, T. (2007). A scaling law for slow earthquakes. Nature, 447(7140), 76-79.
Ide, S. (2012). Variety and spatial heterogeneity of tectonic tremor worldwide. J.Geophys.Res., 117, B03302.
Ishimoto, M., and K. Iida (1939), Observations of earthquakes registered with the microseismograph constructed recently, Bull. Earthquake Res. Inst. Univ. Tokyo, 17, 443 – 478
Ito, Y., Obara, K., Shiomi, K., Sekine, S., and Hirose, H. (2007). Slow earthquakes coincident with episodic tremors and slow slip events. Science, 315(5811), 503-506.
Kao, H., Shao-Ju Shan, Dragert, H., Rogers, G., Cassidy, J. F., and Ramachandran, K. (2005). A wide depth distribution of seismic tremors along the northern cascadia margin. Nature, 436(7052), 841-844.
Kao, H., Thompson, P. J., Rogers, G., Dragert, H., and Spence, G. (2007). Automatic detection and characterization of seismic tremors in northern cascadia. Geophysical Research Letters, 34(16), L16313.
Kim, K., Chiu, J., Pujol, J., Chen, K., Huang, B., Yeh, Y., et al. (2005). Three-dimensional VP and VS structural models associated with the active subduction and collision tectonics in the taiwan region. Geophysical Journal International, 162(1), 204-220.
Kim, M. J., Schwartz, S. Y., and Bannister, S. (2011). Non-volcanic tremor associated with the march 2010 gisborne slow slip event at the hikurangi subduction margin, new zealand. Geophysical Research Letters, 38(14), L14301.
Kirby, S., K. Wang, and T. Brocher (2002), A possible deep, long-term source for water in the Northern San Andreas Fualt System: A ghost of Cascadia subduction past? Eos Trans. AGU, 83, Fall Meet. Suppl., Abstract S22B-1038.
Kodaira, S., Iidaka, T., Kato, A., Park, J., Iwasaki, T., and Kaneda, Y. (2004). High pore fluid pressure may cause silent slip in the nankai trough. Science, 304(5675), 1295-1298.
La Rocca, M., McCausland, W., Galluzzo, D., Malone, S., Saccorotti, G., and Del Pezzo, E. (2005). Array measurements of deep tremor signals in the cascadia subduction zone. Geophysical Research Letters, 32(21), L21319.
Lee, C., Hirata, N., Huang, B., Huang, W., and Tsai, Y. (2010). Evidence of a highly attenuative aseismic zone in the active collision orogen of taiwan. Tectonophysics, 489(1), 128-138.
Lin, C. (2009). Compelling evidence of an aseismic slab beneath central taiwan from a dense linear seismic array. Tectonophysics, 466(3–4), 205-212.
Miller, M. M., Melbourne, T., Johnson, D. J., and Sumner, W. Q. (2002). Periodic slow earthquakes from the cascadia subduction zone. Science, 295(5564), 2423-2423.
Miyazawa, M., and Mori, J. (2006). Evidence suggesting fluid flow beneath japan due to periodic seismic triggering from the 2004 sumatra-andaman earthquake. Geophysical Research Letters, 33(5), L05303.
Nadeau, R. M., and Dolenc, D. (2005). Nonvolcanic tremors deep beneath the san andreas fault. Science, 307(5708), 389-389.
Nadeau, R. M., and Guilhem, A. (2009). Nonvolcanic tremor evolution and the san simeon and parkfield, california, earthquakes. Science, 325(5937), 191-193.
Nakata, R., Suda, N., and Tsuruoka, H. (2008). Non-volcanic tremor resulting from the combined effect of earth tides and slow slip events. Nature Geosci, 1(10), 676-678.
Obara, K. (2002). Nonvolcanic deep tremor associated with subduction in southwest japan. Science, 296(5573), 1679-1681.
Ohta, Y., Freymueller, J. T., Hreinsdóttir, S., and Suito, H. (2006). A large slow slip event and the depth of the seismogenic zone in the south central alaska subduction zone. Earth and Planetary Science Letters, 247(1–2), 108-116.
Payero, J. S., Kostoglodov, V., Shapiro, N., Mikumo, T., Iglesias, A., Pérez-Campos, X., et al. (2008). Nonvolcanic tremor observed in the mexican subduction zone. Geophysical Research Letters, 35(7), L07305.
Peng, Z., and Chao, K. (2008). Non-volcanic tremor beneath the central range in taiwan triggered by the 2001 mw 7.8 kunlun earthquake. Geophysical Journal International, 175(2), 825-829.
Peterson, C. L., and Christensen, D. H. (2009). Possible relationship between nonvolcanic tremor and the 1998–2001 slow slip event, south central alaska. J.Geophys.Res., 114, B06302.
Peterson, C. L., McNutt, S. R., and Christensen, D. H. (2011). Nonvolcanic tremor in the aleutian arc. Bulletin of the Seismological Society of America, 101(6), 3081-3087.
Rau, R., and Wu, F. T. (1995). Tomographic imaging of lithospheric structures under taiwan. Earth and Planetary Science Letters, 133(3–4), 517-532.
Rogers, G., and Dragert, H. (2003). Episodic tremor and slip on the cascadia subduction zone: The chatter of silent slip. Science, 300(5627), 1942-1943.
Rubinstein, J. L., Shelly, D. R., and Ellsworth, W. L. (2010). In Cloetingh S., Negendank J.(Eds.), Non-volcanic tremor: A window into the roots of fault zones Springer Netherlands.
Segall, P., Desmarais, E. K., Shelly, D., Miklius, A., and Cervelli, P. (2006). Earthquakes triggered by silent slip events on kilauea volcano, hawaii. Nature, 444(7116), 235-235.
Seno, T., and Yamasaki, T. (2003). Low-frequency tremors, intraslab and interplate earthquakes in southwest Japan—from a viewpoint of slab dehydration. Geophysical Research Letters, 30(22), 2171.
Shelly, D. R., Beroza, G. C., Ide, S., and Nakamula, S. (2006). Low-frequency earthquakes in shikoku, japan, and their relationship to episodic tremor and slip. Nature, 442(7099), 188-191.
Song, T. A., Helmberger, D. V., Brudzinski, M. R., Clayton, R. W., Davis, P., Pérez-Campos, X., et al. (2009). Subducting slab ultra-slow velocity layer coincident with silent earthquakes in southern mexico. Science, 324(5926), 502-506.
Suda, N., Nakata, R., and Kusumi, T. (2009). An automatic monitoring system for nonvolcanic tremors in southwest japan. J.Geophys.Res., 114, B00A10.
Tang, C., Peng, Z., Chao, K., Chen, C., and Lin, C. (2010). Detecting low-frequency earthquakes within non-volcanic tremor in southern taiwan triggered by the 2005 Mw8.6 nias earthquake. Geophysical Research Letters, 37(16), L16307.
Walter, J. I., Schwartz, S. Y., Protti, J. M., and Gonzalez, V. (2011). Persistent tremor within the northern costa rica seismogenic zone. Geophysical Research Letters, 38(1), L01307.
Watanabe, T., Hiramatsu, Y., and Obara, K. (2007). Scaling relationship between the duration and the amplitude of non-volcanic deep low-frequency tremors. Geophysical Research Letters, 34(7), L07305.
Wech, A. G., and Creager, K. C. (2007). Cascadia tremor polarization evidence for plate interface slip. Geophysical Research Letters, 34(22), L22306.
Wech, A. G., and Creager, K. C. (2008). Automated detection and location of cascadia tremor. Geophysical Research Letters, 35(20), L20302.
Wech, A. G., Boese, C. M., Stern, T. A., and Townend, J. (2012). Tectonic tremor and deep slow slip on the alpine fault. Geophysical Research Letters, 39(10), L10303.
Wu, Y., Chang, C., Zhao, L., Shyu, J. B., Chen, Y., Sieh, K., et al. (2007). Seismic tomography of Taiwan: Improved constraints from a dense network of strong motion stations. J.Geophys.Res., 112, B08312.
Yang, H., Zhu, L., and Chu, R. (2009). Fault-plane determination of the 18 april 2008 mount carmel, illinois, earthquake by detecting and relocating aftershocks. Bulletin of the Seismological Society of America, 99(6), 3413-3420.
Yen Horng-Yuan, Chen Chieh-Hung, Hsieh Hsien-Hsiang, Lin Ching-Ren, Yeh Yih-Hsiung, Tsai Yi-Ben, Liu Jann-Yeng, Yu Guey-Kuen, and Chen Yi-Ru (2008). Magnetic Survey of Taiwan and Its Preliminary Interpretations. Terr. Atmos. Ocean. Sci., Vol. 20, No. 2, 309-314.
許世弘，2009，台灣花蓮地區地震前兆特性研究，國立成功大學地球科學系碩士論文，共88頁。
葉庭禎，2011，台灣地震與長微震之動態誘發，國立台灣大學地科學所碩士論文，共102頁。
彭葦，陳卉瑄，胡植慶 (2012)，中央山脈下方群震和長微震的時空相關性，地球科學的傳承與創新，社團法人中華民國地質學會與中華民國地球物理學會101年年會暨學術研討會，國立中央大學。
薩宜光，2004，台灣中央山脈地震活動性探討，國立成功大學地球科學系碩士論文，共132頁。