Imaging the Eastern Trans-Mexican Volcanic Belt

墨西哥中部跨墨西哥火山带（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巨大变化。向西，俯冲的板块在45公里深的地方是水平的，直到它到达TMVB（在墨西哥城纬度），在那里它进入地幔500公里的深度。在东部，板块以30度的倾角下降到150公里的深度，在那里它被一个无法解释的结构切断。这项研究的目的是了解为什么这些系统是不同的，以及它们是如何协同工作的。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。确定该地区的构造非常重要，因为它是该模式的一个转折点。该研究还将继续与墨西哥科学家在过去十年中一直在进行的合作研究。我们建议使用接收函数来绘制该结构的地下界面，从而绘制出TMVB东端下方结构的详细图像。该方法利用纵波到横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表面波和环境噪声的相关性。这两种技术都可以用来估计地下的各向异性，从而确定物质现在和过去的流动情况。我们的目标是将构造和水流整合到可以用来解释该地区构造演化的模型中。该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），该项目正在该地区运营十几个地震台站，我们计划对这些台站进行成像。

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.