本研究使用廣泛利用於地殼、地函剪力波速度構造研究之接收函數法，對TSMIP測站的高頻資料加以分析，嘗試探求淺部數公里內之速度構造，並對此方法之相關參數加以測試及探討，將之利用於地震測站密集且地震頻繁之蘭陽平原上，以求取各測站下之一維剪力波速度構造，進而推估其速度構造形貌。各測站之接收函數波形明顯隨震源方位角變化，強烈地顯示測站下傾斜構造的存在；且各波相之振幅變化所反應之速度介面，並非只是單純的傾斜平面，而是更為複雜之側向非均質構造。從各測站之剪力波速度構造結果中，可清楚的發現表土層、現世沖積層、更新世地層及基盤的存在及分佈變化。蘭陽平原下之更新統與基盤界面深度在平原邊緣最淺，往平原中央漸漸變深，並在壯圍海邊之深度最深；宜蘭市、羅東東邊之基盤深度呈凹槽狀分佈，而ILA016、018測站附近也可能存在這樣的基盤變化；而沈積層與更新統之界面深度變化範圍在100至400公尺之間，其趨勢與基盤面深度同樣從平原邊緣往海邊變深，但其深度變化梯度明顯較基盤面為緩，且構造變化簡單。此種高頻震波資料之接收函數研究，的確可正確推估測站下之淺層剪力波速度構造，尤其測站密集分佈之區域，可清楚的解析該區域之速度構造變化，進而描繪地下之可能形貌。 In this study, we calculated the shallow shear-velocity structures of Ilan basin by applying the receiver function technique on the acceleration seismograms recorded by TSMIP stations. We have also tested the suitability of this receiver function technique on the high frequency data. From the variations of receiver function waveform with respect to azimuth, we concluded that the structure beneath the stations are very different, such as a dipping plane or large lateral velocity heterogeneity. We can also relate our velocity structure results to the common geology such as topsoil, alluvium, Pleistocene and basement rocks. The depths of the basement rock become very shallow near the edge of plain. And the depths become deeper toward the center of plain and toward the sea. However, the interface become concave near Ilan and Lotung city, and the interface beneath ILA016 and ILA018 has similar variation. The thickness of the alluvium vary between 100 to 400 meters and has a similar trend like the basement, but the surface gradient of depth is smaller, and the structure is simpler.
