台灣地震前兆研究之土壤氣體地球化學觀測及其構造隱示

Continuous Monitoring of Soil Gas Geochemistry for Seismic Precursory Study in Taiwan and its Tectonic Implications

傅慶州(Ching-Chou Fu)

指導教授 ： 楊燦堯

國立臺灣大學/理學院/地質科學研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.00392

摘要

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。

關鍵字

地震前兆 ； 土壤氣體地球化學

並列摘要

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.

並列關鍵字

Seismic Precursory ； Soil Gas Geochemistry

參考文獻

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