Imaging the Eastern Trans-Mexican Volcanic Belt

墨西哥中部横贯墨西哥火山带(TMVB)的突然结束标志着定义北美西部边缘的俯冲系统发生了戏剧性的变化。在西面，俯冲板块是水平的，深度为45公里，直到它到达TMVB(在墨西哥城纬度)，在那里它潜入地幔500公里深。在东边，板块以30度的倾角下降到150公里的深度，在那里被一个无法解释的结构切断。这项研究的目标是了解这些系统为什么不同，以及它们是如何共同发挥作用的。更大的目标是为从美国西海岸到中美洲的俯冲系统找到一个统一的模型。确定该地区的构造很重要，因为它是该模型的一个转折点。这项研究还将继续与墨西哥科学家进行过去十年的合作研究。我们建议在TMVB东端下面制作一张详细的结构图像，使用接收器功能绘制结构中的地下界面。该方法利用P波到S波的转换来确定界面的位置和对比度。为了确定该地区的速度结构，我们将使用来自地震的面波和环境噪声相关性。这两种技术还可以用来估计地下的各向异性行为，这可以用来确定现在和过去的物质流动。其目标是将结构和流动整合到可以用来解释该地区构造演化的模型中。这项研究将利用该地区现有的几个地震数据集，以及目前墨西哥的一个项目(GECO)，该项目正在运营我们计划成像的该地区的十几个地震台站。

The abrupt end of the Trans-Mexican Volcanic Belt (TMVB) in central Mexico marks a dramatic change in the subduction system that defines the western margin of North America. To the west, the subducted slab is horizontal at 45 km depth until it reaches the TMVB (at the latitude Mexico City) where it plunges into the mantle to a depth of 500 km. To the east the slab descends with a dip of 30-degrees to a depth of 150 km where it is cut off by an unexplained structure. The goal of this study is to understand why these systems are different and how they function together. The larger goal is to find a unified model for the subduction system from the western coast of the United States to Central America. Determining the tectonic structure in this region is important, because it is a transition point in that model. The study will also continue cooperative studies with Mexican scientists that have been ongoing for the past decade.We propose to make a detailed image the structure beneath the eastern end of the TMVB, using receiver functions to map subsurface interfaces in the structure. This method uses the conversion of P-waves to S-waves to determine the location and contrast of the interfaces. To determine the velocity structure of the region we will use surface waves from earthquakes and ambient noise correlations. Both of these techniques can also be used to estimate the anisotropic behavior of the subsurface, which can be used to determine the present and past flow of material. The goal is to integrate the structure and flow into models that can be used to explain the tectonic evolution of this area. The study will exploit several existing seismic datasets in the region, plus a current Mexican project (GECO) that is operating a dozen seismic stations in the region that we plan to image.