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  • 學位論文

臺灣高屏地區Sp轉換波相之研究

A Study of Sp Converted Phase Using Strong Ground Motion Records in Kaoping Region, Taiwan

指導教授 : 吳逸民
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摘要


臺灣位於菲律賓海板塊與歐亞大陸板塊之交界帶上,因此地震活動較為頻繁。臺灣有著高密度的地震網,提供了許多的地震紀錄可供相關研究。本研究區域位於臺灣西南方的高屏地區,為一個三角形的沖積平原。利用臺灣強地動觀測計劃(Taiwan Strong Motion Instrumentation Program,TSMIP)於1992年設立至2010年之間,在高屏地區所接收到的地震資料,進行Sp轉換波位置之深度變化分析。在高屏地區的104個TSMIP測站中,使用了62個測站所接收到的地震資料中,選取164個Sp轉換波相,並利用三維速度模型及Sp波與S波的到時差,計算轉換波相產生的深度變化。研究發現在高屏地區Sp波與S波的時間差為東向西增加,並且在麓山帶最南端出現時間差最大值。在研究區域東側的屏東地區,求得的Sp波相轉換深度較淺,大約為4公里至8公里深,與地層剖面進行深度的比對,多數的波轉換位置深度在中新世的烏山層以及長枝坑層。而位於研究區域西側的高雄地區,求得轉換波相深度較深,平均深度為14公里,最深可達17公里,利用三維速度模型深度的變化顯示,此區域呈現低Vp高Vp/Vs之現象,並隨著深度到達17公里後漸漸轉換,推估研究區域內可能具有厚層沉積岩存在;而比對構造上,位於變形前緣的高屏地區,隱沒作用產生增積岩體,因此求得的轉換波深度,也有可能為增楔岩體與地殼的交界面為轉換波生成的深度位置。

並列摘要


Taiwan is located on the boundary of the Philippine Sea Plate and the Eurasian Plate with highly seismicity. Several dense seismic networks are installed in Taiwan and offer a lot of the earthquake records for related studies. The study region, the Kaoping area is a triangle alluvial plain located in the southwestern Taiwan. Accelerograms recorded from 1992 to 2010 by the Taiwan Strong Motion Instrumentation Program (TSMIP) stations are used to study the depth variation of the Sp phase converted point. There are 164 Sp converted phases picked from 104 stations with 3-D velocity model and travel-time difference of S and Sp phases to estimate the converted depth of the Sp phase. Results show that the depths of converted point increase toward the west throughout of the study region. Kaohsiung area is located in western area of Kaoping region. The average depths of converted points in Kaohsiung region is about 14 km with a deepest depth of 17 km. Three-dimensional model shows Kaoping area characterized by a low Vp and high Vp/Vs zone. These signals maybe explain the large depth in this area. These depths also can be the boundary of accretionary prism and oceanic crust in this region. The Pingtung area is located in the eastern area of the study region. The depths of converted points are from 4 to 8 km and distribute around the Wushan formation (Miocene strata). Sandstone-Shale Interface at the Wushan formation beneath the sediment may be the boundary where Sv convert to P wave in the Pingtung area.

並列關鍵字

Sp converted phase Taiwan TSMIP

參考文獻


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