| DC 欄位 |
值 |
語言 |
| DC.contributor | 地球物理研究所 | zh_TW |
| DC.creator | 魏文宏 | zh_TW |
| DC.creator | Wen-Hong Wei | en_US |
| dc.date.accessioned | 2010-8-27T07:39:07Z | |
| dc.date.available | 2010-8-27T07:39:07Z | |
| dc.date.issued | 2010 | |
| dc.identifier.uri | http://ir.lib.ncu.edu.tw:88/thesis/view_etd.asp?URN=966202005 | |
| dc.contributor.department | 地球物理研究所 | zh_TW |
| DC.description | 國立中央大學 | zh_TW |
| DC.description | National Central University | en_US |
| dc.description.abstract | 本研究我們使用在西太平洋海域 (Western Pacific) ，台灣島上的寬頻地震測站 (BATS station) 與日本在琉球島弧上的地震測站 (F-net Station) ，此兩者形成的地震測站陣列，其接收到來自伊豆群島 (Izu-Bonin islands) 至馬里亞納海溝 (Mariana Trench) 一系列隱沒板塊系統上的遠震事件訊號，來探討影響地震事件產生T波訊號以及地震測站接收T波訊號的控制因子。我們透過計算T波訊號的能量 (Gamma Calculation) ，來探究在接收端 (receiver-side) 控制其能量從聲波 (acoustic wave) 轉換地震波 (elastic wave) 效率的決定性因素。我們也將2005年共48個地震事件經過分析後，有17個地震事件是有T波訊號被測站接收到，特別是來自於馬里亞納海溝南端的地震事件，也有較高的機率被測站陣列所接收到其訊號，所以認為這是很好的路徑，用來觀測T波的訊號紀錄，並藉此了解其可能的傳遞模式。
此外，我們透過震源機制的分類後，發現若地震事件為正斷層 (Normal fault) 的形態時，就有極高的機率會產生T波的訊號紀錄，但之前有學者 (Dziak, 2001) 提出不同的看法，認為是走向滑移斷層 (Strike-Slip fault) 的形態，才較容易產生T波訊號。而在馬里亞納海溝的南端，其海底構造的曲度 (curvature) 相當大，也有學者 (Okal, 2001) 提出這可能是造成容易產生T波訊號的原因之一。因此綜合以上兩個因素，還需要進一步的研究，才能得知在震源端部分(Source-side)主要控制產生T波訊號的因素。
至於接收端的部分，台灣的東部海域，有極為陡峭的海底地形構造，使得T波訊號再由聲波轉換成地震波時會更有效率，以至於在台灣東部海岸線上的地震測站，只要是有產生T波訊號的地震事件，這些位在東部的測站都可以收到 T波的訊號紀錄，甚至可以往內陸約50公里的測站都可以收到到 T波的訊號紀錄。而T波波相的入射路徑與海岸線的夾角，若越接近垂直，就有較好的轉換效率，若呈現斜交的狀態，其轉換效率就較差，因此這夾角也是控制地震測站是否能收到T波訊號紀錄的重要因子之一。
| zh_TW |
| dc.description.abstract | We used seismic station array on the margin of the Western Pacific to examine the controlling factors of earthquakes in the Izu-Bonin-Mariana subduction zone to excite T waves. The observed excited T waves in turn were used to investigate the decisive parameters for receiver-side acoustic-to-elastic conversion, in a quantitative fashion by the Gamma calculation. Having examined earthquakes in 2005, 17 out of 48 are T-excited events. We have discovered a preferential source-receiver pair for observations of T waves, namely, earthquakes in the southern Mariana Arc as recorded by stations in East Taiwan coastline.
Additionally, the T-excited events correlate strongly with normal faulting type of earthquakes. While the strong curvature of the mid-SOFAR isobaths in the South Mariana Arc and the nearly perpendicular incidence to the receiver shoreline of earthquakes herein are conceptually attributed the preferential pair, the correlation with normal-faulting earthquakes needs to be cautiously examined by further studies.
On the receiver side, the steeply dipping slopes of the East Taiwan coasts act as efficient interfaces for acoustic-to-elastic conversion. The converted T-waves can be recorded by stations even 50 km inland. The angles between incidence and receiving shoreline also determine the efficiency of receiver-side conversion.
| en_US |
| DC.subject | 海洋低速帶 | zh_TW |
| DC.subject | 聲波 | zh_TW |
| DC.subject | T波 | zh_TW |
| DC.subject | SOFAR channel | en_US |
| DC.subject | acoustic wave | en_US |
| DC.subject | T-phase | en_US |
| DC.title | 由西太平洋地區T波觀測來探討其成因與遠震參數之關係 | zh_TW |
| dc.language.iso | zh-TW | zh-TW |
| DC.title | Scenarios of T-wave Excitation by Teleseismic Earthquakes in the Western Pacific | en_US |
| DC.type | 博碩士論文 | zh_TW |
| DC.type | thesis | en_US |
| DC.publisher | National Central University | en_US |