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Continuous Monitoring of Soil Gas Geochemistry for Seismic Precursory Study in Taiwan and its Tectonic Implications
No full text一般來說，空氣成份與源自地殼深處的氣體組成截然不同，而斷層帶常可成為一個高孔隙的通道，使地底深處的氣體從地殼深處沿著此路徑向上遷移到地表。經由有系統的土壤氣逸氣調查後，選擇位於斷層帶附近的適當位置，設置氣體地球化學觀測站並配合鄰近地區之地殼活動觀測資料，將有助於吾人瞭解該地區之斷層、地震活動與觀測結果之關聯，並進一步觀測其活動可能的前兆訊息與機制。
本研究持續觀測土壤氣體觀測站，分別為大平地觀測站、古坑觀測站、中崙觀測站、池上觀測站和屏東觀測站。我們發現異常的土壤氡氣濃度變化常和即將發生的地震活動有關，而且每個觀測站僅對特定地區的地震活動較為敏感。整合不同測站對於同一地震的異常反應，進而可劃分地球化學觀測站的敏感反應範圍，若同時在數個觀測站發現顯著的土壤氣異常，根據各觀測站異常出現的時間，有助於未來進一步推估地震將發生的位置、時間以及規模。
本研究亦利用時頻分析的方法對於連續的土壤氣體觀測結果進行資料處理，如：希爾伯特-黃轉換(Hilbert–Huang transform)。結果顯示能夠初步濾除掉部分氣象及環境因子的影響，進而有系統及客觀地辨識出土壤氡氣異常與地震活動的關係。Generally, gas compositions are entirely different in air and deep-crust derived components. Active fault zones usually have a higher permeability than surrounding strata, therefore, can provide conduits for gases originated from the deep crust to migrate upward to the surface. It has been recognized that long-term monitoring of gas/fluid composition at appropriate sites and/or near fault zones, was chosen by soil-gas systematically survey is very helpful to understand the mechanism and process of fault/earthquake activity. Furthermore, it may help us to find out potential earthquake precursors in a specific area.
In this paper, we continuously monitor the variations of soil gas at Tapingti station (TPT), Gukeng station (GK), Chunglun station (CL), Chihshang station (CS) and Pingtung station (PT), respectively. We found that many radon anomalies have been observed in soil gas prior to the impending earthquakes occurred. Each station is only sensitive to the seismic events in the specific area. Thus, comparing the pre-seismic events at different monitoring stations, we can further identify the sensitivity zone of each monitoring system and then may be able to predict the epicenter of upcoming earthquake. The relative heights of soil gas anomaly at two or more stations of their respective times of occurrences, could eventually enable satisfactorily precise predictions of the ensuring earthquakes in location, time and magnitude.
Soil gas records were dealt with time-frequency analysis, such as the Hilbert–Huang transform (HHT). After extracting the possible meteorological and environmental effects, we can clearly recognize the anomalous variations of radon concentrations. The results seem to be helpful to quantitatively identify the anomalies related to the seismic activities, can directly achieve the similarity or even better results with high confidence
Recognition of buried fault and/or fracture by soil gas method: an example of the Chaochou Fault
No full text空氣成份與源自於地殼深處的氣體成份截然不同，地表附近深入地殼的斷層或破裂帶，可成為地底深處氣體向上遷移的通道，而使該處地表土壤氣體成份異常。台灣南部潮州斷層為一被地表沖積層覆蓋的活動斷層，本研究沿著幾條明顯穿過構造線的剖面採集土壤氣樣本，進行氦氣、二氧化碳、甲烷、氧氣、氬氣及氮氣等氣體成份的分析，配合鄰近地區已有的地質、地球物理探勘及地形資料，探討潮州斷層之地表分佈。
分析結果顯示土壤氣中氦氣與二氧化碳濃度，在每條剖面的異常值出現處，呈南北向分佈，與已有文獻所報導的潮洲斷層分佈位置吻合。因此在本研究區域內，氦氣與二氧化碳成為指示斷層位置非常有效的氣體。本研究區域的土壤氣體，除了地表之空氣成份以外，還可以辨識出兩個端成份：一為來自深斷裂的氣體，其氦氣異常程度隨著二氧化碳含量增高而增加；另一則源於淺破裂的氣體，其所含之氦氣濃度並未隨著二氧化碳含量升高而有明顯變化，顯示其二氧化碳來自淺處。
氦同位素 (0.52 ~ 1.05 Ra) 顯示，本研究大部分樣本主要成份為空氣，部分可能有地殼氣體成份混合，但無明顯的地函來源。二氧化碳之碳同位素值介於–11.8 ~ –23.4 ‰之間，顯示有機物質與石灰岩混合的結果。氦同位素和碳同位素表示本研究區域的確有多種的氣體來源。由連續的觀測結果亦發現，斷層帶土壤氣體成份的變化，可能與當地的地殼應力變化有關；因此非常適合日後進行斷層活動的監測。The soil-gas method is based on the principle that faults and/or fractures are highly permeable pathways in rock formation where gases can migrate upward from the deep crust and/or mantle and retain their deep-source signatures in the soil cover. This method is adopted because it can give results in short time. In this work, soil-gas compositions are measured and synthesized in conjunction with the geological, geophysical and geomorphological information along the Chaochou Fault, which is considered as an active fault in southern Taiwan.
Soil-gas samples were collected along several traverses crossing the observed structures and analyzed for He, CO2, CH4, O2 + Ar and N2. The results show that both helium and carbon dioxide concentrations in the soil gas have anomalous values at the specific positions in each of the traverses. The trace of these positions coincides with the N-S trending faults and/or fractures, that is, the postulated trend and pattern of the faults in southern Taiwan. Hence, helium and carbon dioxide are useful index gases in this area.
Based on the helium and carbon dioxide concentrations of the soil gases, at least three components are required to explain the observed variations. In addition to the atmospheric air component, two gas sources can be recognized. One is the deep crust component, exhibiting high He and CO2 concentrations, and considered as best indicator for the surface location of fault/fracture zones in the region. The other component could be a shallower gas source with high CO2 concentration and low He concentration. Moreover, helium isotopic compositions of representative samples vary from 0.52 to 1.05 Ra (the 3He/4He ratio of air), illustrating that most samples have soil air component and may be mixed with some crustal component but no significant input of mantle component. Carbon isotopic composition (δ13C) of carbon dioxide in the soil samples vary from –11.8 to –23.4 ‰, which could be the result of mixing between organic and limestone components. Both helium and carbon isotopic results support the multiple gas sources in studied area. Meanwhile, continuous monitoring indicates that soil gas variations at fault zone may be closely related to the local crustal stress and hence, is suitable for further monitoring on fault activity.目 錄
中文摘要……………………………………………………………………… I
英文摘要……………………………………………………………………… II
目錄………………………………………………………………………… IV
表目錄………………………………………………………………………… V
圖目錄………………………………………………………………………… V
壹、前言……………………………………………………………………… 1
貳、研究原理及前人研究…………………………………………………… 5
2-1研究原理……………………………………………………………… 5
2-2土壤逸氣調查的特點………………………………………………… 7
2-3 主要研究氣體之特性………………………………………………… 8
2-3-1氦氣(Helium)…………………………………………………… 8
2-3-2二氧化碳(Carbon dioxide)……………………………………… 9
2-4 台灣地區之土壤氣探勘之概況………………………………………10
參、研究地區地質概況及相關研究………………………………………… 11
肆、採樣與分析……………………………………………………………… 17
4-1野外採樣……………………………………………………………… 17
4-2實驗室分析…………………………………………………………… 17
4-2-1氦氣偵測儀 ……………………………………………………21
4-2-2攜帶式氣相層析儀………………………………………………21
4-2-3氦氣的純化與氦同位素分析……………………………………24
4-2-4二氧化碳的純化與碳同位素分析………………………………25
伍、結果與討論………………………………………………………………27
5-1第一階段調查………………………………………………………… 27
5-1-1土壤氣體異常分佈位置與斷層之相關性………………………31
5-1-2土壤氣體來源……………………………………………………33
5-2第二階段調查………………………………………………………… 34
5-2-1時間因素與土壤氣體的相關性…………………………………37
5-2-2土壤氣體來源……………………………………………………40
5-2-3土壤氣體異常分佈位置與斷層之相關性………………………44
5-3第一階段調查與第二階段調查之比較……………………………… 45
陸、結論………………………………………………………………………47
柒、參考文獻…………………………………………………………………48
捌、附錄………………………………………………………………………55
附錄8-1：本研究相關之論文成果一………………………………………56
附錄8-2：本研究相關之論文成果二………………………………………70
表目錄
表2-1 大氣的主要組成份…………………………………………………… 6
表3-1 土壤氣體的分析結果……………………………………………… 43
圖目錄
圖1-1台灣的構造輪廓和主要構造單元……………………………………2
圖2-1 不同的土壤覆蓋層對於斷層帶上土壤氣成份影響示意圖…………6
圖2-2 不同的土壤覆蓋層對於斷層帶上土壤氣成份影響示意圖…………7
圖3-1 南台灣的數值地形圖與斷層的分佈情形…………………………12
圖3-2台南、高雄地區麓山帶之地質簡圖………………………………13
圖3-3台南、高雄地區麓山帶之地下構造剖面…………………………14
圖3-4 潮州斷層帶的斷層與地形面分佈圖………………………………15
圖3-5 潮州斷層剖面示意圖………………………………………………16
圖4-1 第一階段研究區域的採樣點分佈圖………………………………18
圖4-2 第二階段研究區域的採樣點分佈圖………………………………19
圖4-3 野外採樣土壤氣體的實際情形……………………………………20
圖4-4 採樣示意圖………………………………………………………… 20
圖4-5氦氣偵測儀………………………………………………………… 22
圖4-6氦攜帶式氣相層析儀……………………………………………… 22
圖4-7 GC檢量校正曲線…………………………………………………23
圖4-8 氦氣純化系統示意圖………………………………………………24
圖4-9 二氧化碳純化系統示意圖…………………………………………25
圖5-1 剖面A~F的土壤氣中氦氣與二氧化碳分析結果…………………28
圖5-1(續) 剖面G~L的土壤氣中氦氣與二氧化碳分析結果……………29
圖5-2 土壤氣體濃度異常分佈圖…………………………………………30
圖5-3 斷層帶上覆不同的土壤層對於地表土壤氣成份影響示意圖…31
圖5-4 綜合所有資料所推測的斷層或破裂帶分佈圖……………………32
圖5-5 土壤氣體中氦氣與二氧化碳含量之投圖…………………………33
圖5-6 剖面A~J的土壤氣中氦氣與二氧化碳分析結果…………………35
圖5-6（續） 剖面K~R的土壤氣中氦氣與二氧化碳分析結果……………36
圖5-7 I剖面土壤氣中連續氦氣與二氧化碳的分析結果…………………39
圖5-8 I剖面中土壤氣氦氣的連續觀測結果………………………………40
圖5-9 潮州斷層地區土壤氣樣本氦同位素的三端源圖…………………41
圖5-10 潮州斷層地區土壤氣樣本的碳同位素值…………………………42
圖5-11 土壤氣體中氦氣與二氧化碳含量之投圖…………………………42
圖5-12 綜合第二階段調查所有資料所推測的斷層或破裂帶分佈………45
圖5-13 綜合前述資料而得到的3D的構造模型…………………………4
Reconnaissance of soil gas composition over the buried fault and fracture zone in southern Taiwan
No full textSoil-gas monitoring: A tool for fault delineation studies along Hsinhua Fault (Tainan), Southern Taiwan
No full textGeochemical variation of soil–gas composition for fault trace and earthquake precursory studies along the Hsincheng fault in NW Taiwan
No full textVariations of helium and radon concentrations in soil gases from an active fault zone in southern Taiwan
No full textVariations of soil-gas composition around the active Chihshang Fault in a plate suture zone, eastern Taiwan
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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