Mapping Lithospheric Structure Beneath the Andes from Telesismic Analysis of Depth Phase Precursors

该项目将利用EarthScope的USAray组件以及全球地震网络的适当台站收集的地震数据，探测南美洲安第斯山脉带下的地壳和上地幔。这项研究是基于使用？下面？可以在深度相位pP之前到达的反射信号，以识别和绘制关键的岩石圈不连续面，包括但不限于莫霍面、黑尔不连续面、岩石圈底部和可能的岩浆体。关于安第斯山脉关键地区这种不连续性的存在、程度和性质，pP前兆是目前唯一可获得的信息。它们还提供了一个新的视角，在这些功能的地区，更传统的地震信息（如折射，层析成像，接收器功能）。通过分析来自传统技术中存在大量数据的地区的数据，我们希望改进我们的方法。更重要的是，这些观测结果应能对各种地球动力学模型提供新的检验，这些模型是为了将地壳增厚、构造缩短、高原隆起、岩石圈分层和沿着安第斯型边缘的火山活动联系起来而提出的。安第斯造山带是非碰撞造山的全球原型。因此，它被广泛引用为许多塑造北美西部的过程的现代类似物。因此，我们提出的研究不仅应该促进我们对安第斯山脉的了解，但通过扩展提供新的见解，美国西部的构造。由于该技术仍然是探索性的，在某种程度上，PI将集中精力在最有利可图的方向，特别强调使用最大的地震作为震源和工作的叠加技术。他们希望展示一些处理过程，并走上获得一阶结果的道路。这里要开发/应用的方法不仅代表了地球镜设施在美国以外探测岩石圈结构的相对新颖的用途，它是地震和勘探地震方法的合并，应证明对研究世界上有深层震源的其他区域有用。该奖项支持的研究生代表了连接主动和被动地震文化的培训。这种类型的集成必将成为未来地震学研究的标志。

The PIs will use seismic data collected by the USArray component of EarthScope as well as appropriate stations of the Global Seismic Network (GSN) to probe the crust and upper mantle beneath the Andean mountain belt of South America. This research is based on the use of ?underside? reflected signals which may arrive ahead of the depth phase pP to identify and map key lithospheric discontinuities, including but not limited to the Moho, the Hale discontinuity, the base of the lithosphere and possible magma bodies. pP precursors represent the only currently available information about the existence, extent and nature of such discontinuities in key areas of the Andes. They also offer a new perspective on these features in areas where more conventional seismic information is available (e.g. refraction, tomography, receiver functions). By analyzing data from regions where substantial data exist from conventional techniques, we hope to refine our methodology. More importantly, these observations should provide new tests of the various geodynamic models which have been proposed to relate crustal thickening, tectonic shortening, plateau uplift, lithospheric delamination and volcanism along Andean-type margins. The Andean orogenic belt is the global archetype of non-collisional mountain building. As such it has been extensively cited as hosting the modern analogs for many of the processes that have shaped western North America. Thus our proposed research should not only advance our understanding of the Andes, but by extension provide new insight into the tectonics of the western US.As the technique is still exploratory to some degree, the PIs will focus efforts in the most profitable directions with particular emphasis on using the largest earthquakes as sources and working on the stacking techniques. They hope to demonstrate some of the processing and be on the road to obtaining first order results.The methodology to be developed/applied here not only represents a relatively novel use of EarthScope facilities to probe lithospheric structure outside the U.S., it constitutes a merger of earthquake and exploration seismic methodologies that should prove useful in studying other regions of the world where deep seismic sources are available. The graduate student to be supported by this award represents training that bridges the active and passive seismic cultures. This type of integration is sure to become a hallmark of future seismological investigations.