台中－彰化近海的淺部地層構造

臺灣的造山運動，係因菲律賓海板塊與歐亞大陸板塊之間的碰撞作用而引起，以變形前緣做為地質區塊的分界，也是應變作用的交界，在變形前緣以西沒有顯著的地層變形，而變形前緣以東是剛發育的褶皺逆衝帶。在臺灣造山帶與中國被動大陸邊緣之間的過渡帶在壓應力的作用下產生褶皺逆衝帶，同時發育年輕的斷層與斷層相關褶皺。在褶皺逆衝帶發育的斷層與斷層相關褶皺多為表皮構造，代表在淺部地層發育，並未深入的基盤而是在滑脫面之上。在前人的研究中，有許多描述臺灣西部與西南部因造山運動而岩石圈側向聚合應變的構造特徵，顯少聚焦在鄰近變形前緣的表皮構造，宋國士（2017）研究中顯示臺中－彰化外海有受到擠壓應力所形成的海底臺地，同時觀察到一系列的構造線型，此處即為褶皺逆衝帶。在上述褶皺逆衝帶發育的岩層條件中，可推測對應力的累積較不易，因此地震活動規模不會太大（M < 5），如在宋國士（2017）的研究中，其研究區域內自1900 年以來芮氏規模大於5 的地震僅有一個事件。本研究延續宋國士（2017）的研究，透過電花波源和海底地形資料，結合震源機制，以觀察中彰外海之淺層構造特徵及地震活動機制，並探討區域應力的作用與沿岸平臺形成的成因。

關鍵字

近岸平臺；反射震測法；火花放電；震源機制解

並列摘要

The collision of Philippine Sea plate and Eurasian Plate formed Taiwan orogen and caused development of fold-thrust belt. At this tectonic setting, it attracted researchers to study about the tectonic patterns and mechanisms in this area. Thus, there are lots of prior studies about tectonic patterns in western and southwestern Taiwan offshore, but few studies focus on the surface structure, especially in Taichung Changhua offshore area. It’s obviously to find the plateau along the coastline from the topography in study area, and there are a series of structural lineation beneath the plateau, from seismic profiles, and here is so-called fault-thrust belt. Décollement usually develop in the high porosity and moisture weak layer, shale and evaporate for instance, which means that the strata is unable for endure the accumulation of elastic strain for generating greater earthquake. Analyzing earthquake event data from Central Weather Bureau of Taiwan from 1900 till nowadays, there has only one event with M > 5. In this study, we use seismic reflection profiles from sparker and bathymetry data, and analyze focal mechanism from seismic data, to reveal the surface tectonic features and figure out relationship between these tectonic and seismic events.

並列關鍵字

nearshore plateau ； seismic reflection method ； spark ； focal mechanism

參考文獻

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延伸閱讀

蔡芷怡、丁宗蘇、林佳祈、沈芳伃（2021）。鷸見彰化－彰化沿海地區的鷸鴴們。自然保育季刊，(113)，12-21。https://www.airitilibrary.com/Article/Detail?DocID=16072928-202103-202104070013-202104070013-12-21
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國際替代計量

台中－彰化近海的淺部地層構造

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