碩士 / 國立中央大學 / 遙測科技碩士學位學程 / 102 / Guishan Island is located at north eastern Taiwan belongs to Yilan County. According to geophysical and geochemical studies, Guishan Island is an active volcano, and the latest eruption occurred in the Holocene (7 ka). The active hydrothermal vents and earthquake can be considered as manifestations of volcanic activity. There are some hydrothermal vents at eastern offshore, and the fluids from the vents are mostly made up of sulfur, which cause the discoloration of the ocean around Guishan Island. The discolored area is called plume which can be easily detected by satellite image. The shape and size of plume are disturbed by ocean currents or winds. In this study, we detect the plume area by three steps: (1) remove land area; (2) remove cloud area; (3) classification. First, ENVI is used to build a mask and remove land area. Followed by a fully constrained least squares approach, it is a mixed pixel classification method for concentration estimation in each pixel. Finally, the area of plume is calculated from the result of least square approach, and then compare with the number of earthquake events to find the relationship between them. In our experiment, 36 SPOT images in 2008 are adopted, and the result shows that the larger area of plume was occurred around the large cluster of events. The area of plume is related to earthquake but there isn't clear. After the correlation coefficient is calculated, the result shows the area of plume is related to the number of earthquake events. The highest correlation coefficient is 0.68 in ±1day. It means maybe the earthquakes can cause the area of plume become larger.
The number of earthquake event is 425 and the number of image is 36. Although the number is uneven, the best way for long term monitor is satellite image until there is a direct measurement.
| Identifer | oai:union.ndltd.org:TW/102NCU05105065 |
| Date | January 2014 |
| Creators | Yu-wen Li, 李聿文 |
| Contributors | Chung-pai Chang, Hsuan Ren, 張中白, 任玄 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 76 |
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