Collaborative Research: Mapping Melt and Matrix Flow in the Uppermost Mantle: Undershooting the East Pacific Rise between Siqueiros and Clipperton

在北纬8度至10度之间的东太平洋海隆上进行的这一“下冲”实验将利用地震速度和衰减以及Pn波到达的异常，以及Sn波（如果观测到的话），绘制沿海隆轴沿着地壳底部附近熔体垂直分布的公里级变化。 Pn速度各向异性的大小和方向将被用来约束莫霍面附近地幔流的方向。 该项目的目标是：（1）绘制沿整个区段上地幔沿着的地震速度和衰减结构的轴向变化图，（2）绘制上地幔各向异性的方向和大小图，（3）确定三个对比点的增生轴正下方的最低地壳、莫霍面过渡带和上地幔的垂直结构，（4）测量沿着整个变换边界脊段的地壳厚度变化，（5）将结果与现有的观测和分段模型进行比较。

This "undershooting" experiment, on the East Pacific Rise between 8 and 10 degrees north, will use seismic velocity and attenuation and anomalies of Pn arrivals, and Sn waves if they are observed, to map km-scale variations in the vertical distribution on melt near the base of the crust along the ridge axis. The magnitude and orientation of anisotropy in Pn velocities will be used to constrain the direction of mantle flow near the Moho. The goals of the project are to: (1) map along-axis variations in the seismic velocity and attenuation structure of the uppermost mantle along he entire segment, (2) map the orientation and magnitude of anisotropy in the uppermost mantle, (3) determine the vertical structure of the lowermost crust, Moho transition zone, and uppermost mantle directly beneath the axis of accretion at three contrasting sites, (4) measure crustal thickness variations along an entire transform-bounded ridge segment, and (5) compare the results with existing observations and models of segmentation.