Broadband Seismological Investigations of Earth Structure and Earthquake Sources

地球结构和震源的宽带地震研究

• 批准号: 0635570
• 负责人: Thorne Lay
• 金额: $ 52.38万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0635570&HistoricalAwards=false
• 关键词: Broadband; Seismological; Investigations; Earth; Structure

This is a four-year project supporting the seismological research program conducted by Thorne Lay at the University of California, Santa Cruz. The unifying theme of the research effort is the use of broadband digital seismic data to address fundamental questions about earth structure and earthquake rupture processes. The research is focused on the following areas: (1) seismic wave stacking and migration is being used to image lowermost mantle structure, testing the hypothesis that the post-perovskite phase transition occurs near the top of the D" region, and seeking evidence of a deeper reverse transformation to perovskite above the core-mantle boundary that can constrain thermal gradients in the CMB boundary layer; (2) analysis of large data sets to separate source, receiver and deep propagation complexity is being pursued, seeking to better understand near-source (slab) contributions to waveform complexity and shear wave splitting; (3) stacking and migration of seismograms from deep focus earthquakes is being performed to develop images of upper mantle reflectivity in the vicinity of subduction zones; and (4) analysis of moderate-size earthquake source properties along the Sumatra-Andaman rupture zone and other regions of oblique subduction will be conducted to assess variations in frictional properties. Current advances associated with this research include the first direct determination of heat flux through the core-mantle boundary based on seismological and mineral physics constraints, detection of strong scattering in localized patches at the core-mantle boundary, and three-dimensional imaging of multiple seismic discontinuities in the upper mantle beneath Tonga. This overall research effort involves the PI and two graduate students, with continuing collaborations with colleagues at other institutions. We anticipate continued progress in characterizing dynamical processes associated with the Earth's major boundary layers near the surface and near the core-mantle boundary.

这是一个为期四年的项目，支持由加州大学圣克鲁斯分校的索恩·雷主持的地震学研究项目。研究工作的统一主题是使用宽带数字地震数据来解决有关地球结构和地震破裂过程的基本问题。主要研究方向为：(1)利用地震波叠加与偏移成像底层地幔结构，验证后钙钛矿相变发生在D”区顶部附近的假设，寻找在核心-地幔边界上方钙钛矿更深层次反向转变的证据，从而约束CMB边界层的热梯度；(2)对大数据集进行分析，以分离源、接收和深度传播复杂性，寻求更好地理解近源（slab）对波形复杂性和横波分裂的贡献；(3)对深震源地震的地震记录进行叠加和偏移，形成俯冲带附近的上地幔反射率图像；(4)沿苏门答腊-安达曼断裂带和其他斜俯冲区域进行中等震源性质分析，以评估摩擦性质的变化。目前与该研究相关的进展包括：基于地震学和矿物物理约束，首次直接确定通过核-幔边界的热通量；探测核-幔边界局部斑块的强散射；汤加上地幔多个地震不连续体的三维成像。这项全面的研究工作涉及PI和两名研究生，并与其他机构的同事继续合作。我们期望在描述与地球表面和核幔边界附近的主要边界层有关的动力学过程方面继续取得进展。