CAREER: (An)elastic mantle structure based on 3D wave simulations & full waveform inversion: From GLobal ADjoint models to visualization of Slabs, Plumes And Convection in MANt

地震产生的地震波在全球各地传播，并携带来自地球深处的信息。地震学家分析这些地震波，并与模拟数据进行比较，以阐明地球内部的复杂性。然后，这些测量被用于一种名为地震层析成像的技术，类似于医学层析成像，以获得根据地震参数对地壳和地幔进行3D CAT扫描的图像。超级计算机和数值方法的进步，加上近年来地震数据质量和数量的增加，为提高基于三维数值波浪模拟的层析图像的分辨率提供了新的机会。高分辨率的地球内部现今快照对于了解地幔过去和现在的动态至关重要，地幔通过地震和火山活动等构造过程塑造了我们星球的表面。更高分辨率的模型对于更好地了解地震的来源和准确定位也是至关重要的，从工程角度来看，需要更高分辨率的模型来评估地震危险和探测核爆炸。为了促进为研究和教育活动有效地探索地幔，所建立的模型将与来自其他学科的数据一起用于设计一个互动、协作的地球模型SPAC-MAN(地幔中的板块、羽流和对流)，用于在虚拟和增强现实环境和天文馆中进行可视化。与丹佛自然与历史博物馆的合作将覆盖从儿童到成人的一系列年龄段，在促进STEM领域的同时，教育他们了解我们星球的内部及其动力学。地幔的多尺度结构的地震成像为构建和理解当今的地幔动力学提供了基本约束。衰减是衡量地震波能量损失的指标，是探测地幔部分熔融、热变化和水分含量的关键参数。由于衰减也可能显著影响地震震相的到达时间，因此波速模型和衰减模型应同时构建。这项职业计划的目标是基于三维地震波模拟和同时建立地震波速和衰减模型来研究地幔的多尺度结构。还将探索来自海洋的新兴数据集，以便在地震层析成像中吸收它们，以特别提高海洋下的分辨率。地震层析成像处于这样一个阶段，即进一步提高分辨率需要使用波传播的全部物理原理。伴随层析成像是一种全波形反演技术，它有效地利用了3D波模拟，从而避免了经典地震层析成像中常用的近似和校正，从而产生了纯数据驱动的地球内部地震模型。这项职业计划的目标是在三维波浪模拟和全波形反演的基础上，对地幔的多尺度(AN)弹性结构提供新的约束。为此，(1)在全球全波形反演的基础上，通过同时反演滞弹性参数和弹性参数，建立了滞弹性全球地幔模型，避免了因忽略散射/散焦效应而可能产生的偏差。(2)将通过它们的正演模拟研究整个地幔的多尺度非均质性；(3)将建立一个框架，将来自海洋的新兴数据集同化为全球伴随反演，以提高全球数据覆盖率和海洋羽流的分辨率。项目成果将为矿物物理学家和地球动力学家提供关键参数，以更好地洞察地球的组成和热演化，促进跨学科研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Seismic waves generated by earthquakes travel all around the globe and carry information from the deep interior of our planet. Seismologists analyze these seismic waves and make measurements compared to simulated data to illuminate the complexities of the Earth's interior. The measurements are then used in a technique called seismic tomography, similar to medical tomography, to obtain 3D CAT-scan images of the crust and mantle in terms of seismic parameters. Advances in supercomputers and numerical methods, together with the increase in the quality and amount of seismic data in recent years, have provided new opportunities to improve the resolution of tomographic images based on 3 dimensional numerical wave simulations. High-resolution present-day snapshots of Earth's interior are essential for understanding the past and present dynamics of the mantle, which shape the surface of our planet through tectonic processes such as earthquakes and volcanic activities. Higher-resolution models are also crucial for better understanding the source of earthquakes, accurately locating them, and are required from an engineering point of view to assess seismic hazard and to detect nuclear explosions. To facilitate effective exploration of Earth's mantle for research and educational activities, constructed models together with data from other disciplines will be used to design an interactive, collaborative Earth model, SPAC-MAN (Slabs, Plumes And Convection in MANtle), for visualization in virtual and augmented reality environments and planetariums. The collaboration with the Denver Museum of Nature & History will reach a range of age groups from children to adults, educating them on the interior of our planet and its dynamics while promoting STEM fields.Seismic imaging of the mantle's multi-scale structure provides fundamental constraints to frame and understand present-day mantle dynamics. Attenuation, a measure of the energy loss of seismic waves, is a key parameter to detect partial melt, thermal variations, and water content in the mantle. Since attenuation may also significantly affect arrival times of seismic phases, wavespeed and attenuation models should be constructed together simultaneously. The goal of this CAREER proposal is to investigate the multi-scale structure of the mantle based on 3D seismic wave simulations and the simultaneous construction of seismic wavespeed and attenuation models. Emerging data sets from oceans will also be explored to assimilate them in seismic tomography to specifically improve the resolution underneath oceans. Seismic tomography is at a stage where further refinements in the resolution require the use of full physics of wave propagation. Adjoint tomography, a full-waveform inversion technique, efficiently takes advantage of 3D wave simulations leading to pure data-driven seismic models of the Earth's interior avoiding commonly used approximations and corrections in classical seismic tomography. The goal of this CAREER proposal is to provide new constraints on the multi-scale (an)elastic structure of Earth's mantle based on 3D wave simulations and full-waveform inversion. To this end, (1) an anelastic global mantle model will be constructed by simultaneously inverting for anelastic and elastic parameters based on global full-waveform inversion, which will avoid bias that may come from ignoring scattering/defocusing effects. (2) multi-scale heterogeneity throughout the mantle will be investigated through their forward modeling, (3) a framework will be constructed to assimilate emerging data sets from oceans into global adjoint inversions to improve global data coverage and the resolution of oceanic plumes. The project outcomes will provide critical parameters to mineral physicists and geodynamicists to have better insight into the composition and thermal evolution of our planet, facilitating interdisciplinary research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.