Collaborative Research: High-resolution receiver function imaging of crustal structure in the Southern Great Basin, Nevada

合作研究：内华达州南部大盆地地壳结构的高分辨率接收函数成像

• 批准号: 0838509
• 负责人: Vera Schulte-Pelkum
• 金额: $ 7.56万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-15 至 2012-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838509&HistoricalAwards=false
• 关键词: Collaborative; Research; resolution; receiver; function

The western United States is continuously being deformed by plate tectonicforces. In this study area centered on the southern half of Nevada, thecharacteristic alternating ranges and valleys of Nevada were formed inthe past by stretching of the Earth's crust, and more recently, thenorthwestward motion of the western US coastal regions relative to thecore of the continent. Northwestward plate motion responsible for the SanAndreas Fault is partly also accommodated by a fault system in theCalifornia/Nevada border area. At 15 to 30 km depth, lower crustalrocks are under high enough temperature and pressure to deform withoutbrittle failure. How faulting and surface motions relate to lower crustaldeformation is largely unknown. Our study will use seismic recordings from the University of Nevada, Reno Southern Great Basin Digital Seismic Network to study this process. This network detects signals from worldwide earthquakes after they are modified by the structure of the crustunder the study area. By looking at the differences betweenearthquake signals arriving from different directions, the researchers can find signs of the deformation processes occuring in the lower crust. There areseveral ways in which the lower crust could behave during stretching andshearing of the crust. mong methods to estimate Moho depth and to detectand measure crustal anisotropy, receiver functions offer one of the bestoptions. Using a data set collected by the University of Nevada, Reno'sshort-period, dense, long-running Southern Great Basin Digital SeismicNetwork, they performed a pilot study showing that high-quality receiver functions can be obtained from the data. The receiver functions show arrivals from the Moho as well as from crustal structure, and indicate the presence of anisotropy, scattering, and 3-dimensional structure. The project plan is to apply multichannel stacking techniques, including ones specific to anisotropy detection, a new bootstrap windowing technique for receiver function calculation, and numerical forward modeling in order to distinguish scattering from anisotropic conversions and to detect crustal structures associated with tectonic processes. Receiver functions will be calibrated against permanent and temporary broadband stations in the area, including a handful of broadband stations colocated with the short-period sensors in the same network. Crustal structure and anisotropy findings will be interpreted in the context of the tectonic history and development of southwest Nevada and eastern California in particular, and lower crustal deformation in general.Distinguishing which processes are operating in thisstudy area may help other geoscientists who look at deforming continentalcrust understand similar activity in their field areas. Understandingcrustal deformation, including what happens in the lower crust, isfoundational for studies of faulting and earthquakes in the US andelsewhere.

美国西部不断被板块构造构成。在以内华达州南部为中心的这一研究区域中，在过去的范围和内华达州的山谷中，通过伸展地球的地壳，而最近，在美国西部沿海地区的运动相对于大陆景点，就形成了内华达州的交替范围和山谷。 在内华达州/内华达州边境区域的断层系统中，负责Sanandreas断层的西北板运动也部分适应。 在15至30公里的深度时，下层甲状腺在足够高的温度和压力下以变形而不会破坏。 断层和表面运动与较低的甲壳类信息的关系如何在很大程度上未知。我们的研究将使用内华达大学Reno Southern Great Basin数字地震网络的地震记录来研究这一过程。该网络通过研究区域的结构修饰了全球地震的信号。通过查看从不同方向到达的术后信号之间的差异，研究人员可以找到下层外壳中发生的变形过程的迹象。在地壳的拉伸和剪切过程中，有较低的地壳可以表现出来的阿雷斯族。 MONG估算Moho深度并检测和测量地壳各向异性的方法，接收器功能提供了一种最佳选择之一。他们使用内华达大学（Reno'sshort-Period）收集的数据集，密集的，长期持续的南部伟大的盆地数字地震网络，进行了一项试点研究，表明可以从数据中获得高质量的接收器功能。接收器函数显示来自Moho和地壳结构的到来，并表明存在各向异性，散射和3维结构。该项目计划是应用多通道堆叠技术，包括针对接收器功能计算的新的引导窗口窗口技术以及数值向前建模，以区分散射与各向异性转换和检测与构造过程相关的外壳结构。接收器功能将针对该地区的永久和临时宽带站进行校准，其中包括与同一网络中短期传感器共关联的少数宽带站。 地壳结构和各向异性发现将在内华达州西南部和加利福尼亚东部的构造历史和发展的背景下进行解释，通常在一般中的地壳变形。了解其现场领域的类似活动。了解壳变形，包括在下层地壳中发生的情况，是对美国安德尔斯的断层和地震的研究。