An Analysis of Upper Mantle Heterogeneity and Anisotropy in Western North America Using Recordings Broadband Permanent and Temporary (PASSCAL) Seismic Stations

利用宽带永久和临时 (PASSCAL) 地震台记录分析北美西部上地幔的异质性和各向异性

• 批准号: 9814565
• 负责人: James Gaherty
• 金额: $ 8.08万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-15 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814565&HistoricalAwards=false
• 关键词: Analysis; Upper; Mantle; Heterogeneity; Anisotropy

9814565GahertyThis research involves the determination of seismic heterogeneity and anisotropy in the upper mantle beneath North America using two complementary analyses of surface and body waves recorded at broadband stations across the continent. Data will be retrieved from the Global Seismic Network (GSN), the U.S. National Seismic Network (USNSN), and numerous temporary deployments of the high-capability PASSCAL seismometers. Two new analysis techniques will be applied to explore the nature of seismic anisotropy and its relationship to the tectonic behavior and evolution of the continent. The first technique involves multi-station differential phase-delay analysis applied to fundamental and higher-mode surface waves, both Love and Rayleigh waves, propagating across the array at various azimuths. The data will be inverted for a three-dimensional model of azimuthal anisotropy, with length scales spanning roughly a few 100 km to a few 1000 km. The second technique involves measuring S-wave splitting time separations throughout the region. Depth sensitivity is achieved through the use of a variety of body- and surface-wave phases. Application of these techniques to shear wave propagation across North America will illuminate the basic geodynamic processes giving rise to seismic anisotropy in the upper mantle.

9814565Gaherty这项研究涉及到北美下地幔的地震不均匀性和各向异性的确定，使用两个互补的分析地面和体波记录在整个大陆的宽带站。 数据将从全球地震台网（GSN）、美国国家地震台网（USNSN）和许多临时部署的高性能PASSCAL地震仪中检索。 将采用两种新的分析技术来探讨地震各向异性的性质及其与大陆构造行为和演变的关系。 第一种技术涉及多站差分相位延迟分析，适用于基本的和更高模式的表面波，爱和瑞利波，在各个方位角的阵列传播。 这些数据将被反演为方位各向异性的三维模型，其长度尺度大约为100公里到1000公里。 第二种技术涉及测量整个区域的S波分裂时间间隔。 深度灵敏度是通过使用各种体波和表面波相位来实现的。 将这些技术应用于横跨北美的剪切波传播，将阐明引起上地幔地震各向异性的基本地球动力学过程。