Crust-mantle boundary contraints from ambient noise autocorrelations in North America

北美环境噪声自相关对壳幔边界的约束

• 批准号: 1247020
• 负责人: Ileana Tibuleac
• 金额: $ 8.55万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1247020&HistoricalAwards=false
• 关键词: Crust; mantle; boundary; contraints; ambient

The mantle lithosphere and asthenosphere hold a key to tectonic processes in the Sierra Nevada (SN) and the adjacent provinces. Although addressed by many innovative studies, the causes of differences in the mountain range uplift (higher in the southern SN compared to the uplift in the northern SN), the cause of dramatic variations in SN crustal thickness from east to west, of crustal layering and local "brightness", and the mantle wave speeds relation to topography and surface geology are still under debate. New, independent constraints on crust-mantle boundary (Moho) would help answer these questions, however, Moho depth and properties are often difficult to resolve seismically because of the lack of favorable spatial distribution of source and receiver geometries. The goal of this project is to apply a new method for crust-mantle boundary analysis, which, in contrast to receiver functions, does not depend on large recorded seismic events. Also, in contrast to current reflection/refraction seismic studies, the new method is applied locally at all available seismic sensors, providing unprecedented resolution. The investigators aim to estimate and interpret new, independent models of the depth of the crust ? mantle boundary (Moho discontinuity) across the Sierra Nevada, through analysis of the body wave component (P and S) of Green's Functions extracted from ambient noise autocorrelations. They will use ambient-noise seismic interferometry to extract the crust-mantle boundary Green's Function reflection component. Our activity consists of three stages, as follows:1) Update an existing, comprehensive seismic database in the study area, including P/S seismic velocity models and receiver functions, from publicly available information; 2) Apply ambient-seismic noise autocorrelations to each available sensor in the study area, with the purpose to identify, extract and analyze the P/S reflection component of the Green's Functions. 3) Estimate to the first order the new crustal models using waveform modeling; statistically compare with receiver function estimates and interpret the results in terms of the tested hypotheses. In this project they are applying an innovative data processing method named seismic interferometry to estimate the crust-mantle boundary depth and properties. The study is expected to provide new, independent seismic crustal model constraints for western North America, with focus on the Sierra Nevada and the adjacent regions. In contrast to other currently used procedures, such as receiver function estimates, our method does not depend on large recorded seismic events. This new method also has unprecedented resolution, when applied at all available seismic sensors

地幔岩石圈和软流圈是内华达州山脉及其邻近地区构造过程的关键。尽管许多创新性的研究都提到了这一点，但山脉隆起差异的原因（SN南部的隆起高于SN北方的隆起）、SN地壳厚度从东到西的剧烈变化、地壳分层和局部“亮度”的原因以及与地形和地表地质有关的地幔波速的原因仍在争论之中。新的，独立的壳幔边界（莫霍面）的约束将有助于回答这些问题，然而，莫霍面深度和属性往往是难以解决的地震，因为缺乏有利的空间分布的源和接收器的几何形状。该项目的目标是应用一种新的壳幔边界分析方法，与接收器功能不同，这种方法不依赖于记录的大地震事件。此外，与目前的反射/折射地震研究相比，新方法在所有现有的地震传感器上局部应用，提供了前所未有的分辨率。研究人员的目标是估计和解释新的，独立的地壳深度模型？地幔边界（莫霍面不连续性）横跨Sierra内华达州，通过分析的体波分量（P和S）的绿色的功能提取的环境噪声自相关。他们将使用环境噪声地震干涉测量法提取壳幔边界绿色函数反射分量。我们的活动包括三个阶段，如下：1）更新现有的，全面的地震数据库在研究区，包括P/S地震速度模型和接收器功能，从公开的信息; 2）应用环境地震噪声自相关的每个可用的传感器在研究区，目的是识别，提取和分析的P/S反射分量的绿色的功能。3)利用波形模型对新的地壳模型进行一阶估计，与接收函数估计进行统计比较，并根据检验的假设解释结果。在这个项目中，他们正在应用一种称为地震干涉测量的创新数据处理方法来估计壳幔边界的深度和性质。预计这项研究将为北美西部提供新的、独立的地震地壳模型约束，重点是内华达州山脉和邻近地区。与其他目前使用的程序，如接收函数估计，我们的方法不依赖于大记录的地震事件。当应用于所有可用的地震传感器时，这种新方法也具有前所未有的分辨率