位於台灣北端的大屯火山群，噴發活動停止於三十多萬年前。主要地質構造特徵為金山斷層與崁腳斷層，後火山活動之地熱、溫泉與地震多發生在兩斷層間。本研究利用1996~2001年大屯山K2及PANDA II微震網所收到的資料，挑選品質較佳的304個網內地震，共1872個P波、410個S波，在逆時針旋轉40度、間隔3 x 3公里的格點模型中，使用圓弧波線追跡法，加以重新定位震源與逆推地下速度分佈，所得結果為本區上部地殼之三維速度構造。結果顯示，本區之微震活動在監測的五年內維持穩定的發生頻率。
英文摘要
The Tatun volcanic area is situated at the northern tip of Taiwan. Although the volcanic activity is now extinct, hydrothermal activity in the form of hot springs, high heat flow and earthquakes is still going on. In this study we have inverted P- and S-wave arrival times picked from 304 local earthquakes recorded by a local temporary network during the period of 1996-2001. The tomographic method we have used involves a 3-D circular ray tracing technique through a 3 x 3 km grid rotated at 40°. The results of this tomographic study indicate strong lateral velocity variations, with low velocity bodies probably representing zones of hydrothermal fluid circulation and high velocity areas representing solidified magmatic intrusions.
