Continuous Monitoring of Soil Gas Geochemistry for Seismic Precursory Study in Taiwan and its Tectonic Implications
Date Issued
2012
Date
2012
Author(s)
Fu, Ching-Chou
Abstract
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.
Subjects
Seismic Precursory
Soil Gas Geochemistry
Type
thesis
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