Seismological Components of the MELT Experiment on the Southern East Pacific Rise

9406146奥尔卡特这个实验的目的是提供对大洋中脊下熔体分布和上升流模式的直接观测约束。利用海底仪器阵列研究地幔中的电磁波和地震波传播，将提供可以反演的测量结果，以找出速度和传导性结构的水平和垂直变化，可用于检验流动的理论模型。一组47个海底地震仪将部署在南17度的东太平洋隆起上，为期六个月，以记录远震和地区性震源。该台阵记录的P波和S波以及其他体波震相和勒夫面波和瑞利面波将被用来探测距离海脊轴线100~200公里到几百公里的地幔结构的横向变化。主要目标是确定在山脊轴线正下方是否存在高熔体浓度和低地震速度的狭窄区域，并绘制其垂直和水平范围图。另一个目标是限制上升流的模式。***

9406146 Orcutt This experiment is designed to provide direct observational constraints on the distribution of melt and the pattern of upwelling beneath a mid-ocean ridge. Studies of electromagnetic and seismic wave propagation in the mantle with arrays of ocean- bottom instruments will furnish measurements that can be inverted to find horizontal and vertical variations in velocity and conductivity structure that can be used to test theoretical models of flow. An array of 47 ocean-bottom seismometers will be deployed for six months on the East Pacific Rise at about 17 degrees south to record teleseismic and regional earthquake sources. P and S waves, as well as other body wave phases and Love and Rayleigh surface waves recorded by the array will be used to probe lateral variations in mantle structure to a depth of 100 to 200 km and out to several hundred km from the ridge axis. The mail goal is to establish whether there is a narrow region of high melt concentration and low seismic velocities directly beneath the ridge axis and to map its vertical and horizontal extent. Another goal is to constrain the pattern of upwelling. ***