High Resolution Seismic Experiments Aimed at Mapping Dynamical Processes within Earth's Interior

在这项资助的4年期间，PI Garnero和他在亚利桑那州立大学的团队正在对地球结构进行地震学分析，这些分析与地球内部化学和动力学的重要问题有关。利用宽带和短周期阵列数据，围绕深部地幔和核幔边界区域以及上地幔和过渡带区域展开调查。通过直接波形分析以及叠加和偏移实验对数据进行表征。波形和走时数据通过数射线追踪和波形合成方法建模。该小组最近对夏威夷和南美洲地下的上地幔过渡带（TZ）和不连续结构的高分辨率成像，正得到其他地理区域密集数据覆盖的支持。上地幔不连续地形与地表构造具有很强的相关性。地球深部研究主要集中在高分辨率分析D ‘ ’不连续结构及其与后钙钛矿假说的关系，超低速带结构及其与大型密集热化学桩和羽流起生的关系，以及进一步解决大型低剪切速度省（即太平洋和非洲）的性质。PP的短周期前体被认为是西南太平洋俯冲带下深板块（1000公里以下）的反射。正在进行的分析包括更大的数据集，以及新的波场迁移分析，以探测所有下地幔深度的板块反射。正在收集外核和内芯探测器的大量数据集。它们被用来研究最外层的核，其特征是p波速度降低，以及使用反射波（如PKIIKP）研究内核边界的特性。上述分析旨在提高形成地球内部结构、化学、动力学和进化的内聚理论的能力。更广泛的影响包括对研究生的支持和培训。

In the 4 year period of this grant, PI Garnero and his group at Arizona State University are employing seismological analyses of Earth structure that relate to important questions on Earth's internal chemistry and dynamics. Using broadband and short period array data, investigations are centering on the deep mantle and core mantle boundary region, as well as the upper mantle and transition zone regions. Data are being characterized by direct waveform analyses, as well as by stacking and migration experiments. Wavefom and travel time data are modeled by a number ray tracing and waveform synthesis methods. The group's recent high resolution imaging of the upper mantle transition zone (TZ) and discontinuity structure beneath Hawaii and South America is being bolstered by dense data coverage in other geographic regions. Upper mantle discontinuity topography is showing a strong correlation with surface tectonics. Deep Earth research is centering on high resolution analyses of D" discontinuity structure and how it relates to the post-perovskite hypothesis, ultralow velocity zone structure and how it might relate to large dense thermochemical piles and plume initiation, and further resolution of the nature of the large low shear velocity provinces, namely beneath the Pacific Ocean and Africa. Short-period precursors to PP have been attributed to reflections off of deep slabs (to 1000 km) beneath SW Pacific subduction zones. Analyses underway involve much larger data sets, and new wavefield migration analyses to detect slab reflections at all lower mantle depths. Large data sets of outer and inner core probes are being collected. These are being used to study the outermost core, which has been characterized with reduced P-wave speeds, and properties of the inner core boundary using reflected waves, such as PKIIKP. The analyses described above are aimed at advancing abilities to form cohesive theories of Earth interior structure, chemistry, dynamics, and evolution. Further broader impacts include the support and training of a graduate student.