Consideration of seismic tectonics around southern region of Nansei-shoto Islands by Japan-Taiwan Collaborative research-Regional features of subduction zone-

在本研究中，我们在台湾中部及海岸山脉附近进行地震折射构造勘探。自2004年以来，研究人员在4个采石场完成了25次调查。在这些地点共建立了298个台站，为SRSES记录数据。为了帮助利用挖掘前爆破记录的数据推断地下岩层结构的细节，研究人员编制了两座山脉之间的七个调查剖面（线A-G）。调查使用了Mark Products Company型号的L-22 D地震仪，采样率为200 Hz。Hakusan Industry Datamark LS 8000数字记录仪用于记录地震仪和GPS接收器的数据，精度为3 ms。D线的波形记录清楚地说明了P波的传播，并提供了距离爆炸震中30公里的观测数据。观测到的E线和F线由于其位置环绕海岸山脉而特别重要。D线走时图显示，在SP3附近的表层传播速度为4.8km/s，这一点也可由地表露头的证据证实，即表层是由大理石组成的。次表层的波传播速度为6.0 km/sec。在第三层没有观察到折射波，即使在本研究中使用的距离震中50公里的最大距离。

In this study, we carried out Seismic Refraction Structural Exploration Survey (SRSES) in the vicinity of Taiwan's Central and Coastal mountain ranges. Since 2004, researchers have completed 25 surveys at 4 quarried locations. These locations have a total of 298 stations established to log data for the SRSES. To aid in inferring details of underground rock formation structure using data logged during pre-excavation blasting, researchers have compiled seven survey profiles (lines A-G) between the two mountain ranges.The survey uses the Mark Products Company model L-22D seismometer, operating at a sampling rate of 200Hz. A Hakusan Industry Datamark LS8000 digital recorder is used for logging data from both the seismometer as well as signals from a GPS receiver at a precision of 3ms.The wave form records of line D clearly illustrate the propagation of P-waves and provide observation data up to 30km from the blast epicenter. Observed lines E and F are particularly important due to their locations surrounding the Coastal range. It is suggested that the wave form records on the coastal-side of the mountains be continually monitored for future study.The travel time plot of line D shows a propagation speed of 4.8km/sec on the surface layer around shock point 3 (SP3), which can also be verified by evidence of exposed outcrops that the surface layer is composed of marble. The subsurface layer exhibits a wave propagation speed of 6.0km/sec. Refraction waves are not observed in the third layer, even at the maximum distance used in this study of 50km from the epicenter.