CSEDI Collaborative Research: Anelastic properties of the Earth from seismic to tidal timescale

地震产生的声波在地球内部传播，从而对其传播路径上的条件进行采样。大量到达的声波的集合被用来重建地球内部的条件和结构。在穿过内陆时，这些波会在它们所经过的岩石中产生微观应变。岩石对这些菌株的反应取决于温度和化学环境等条件。俯冲带中的极大地震，例如2004年的安达曼-苏门答腊岛地震或1964年的阿拉斯加地震，产生的能量足以让地球像钟声一样响起。地球与月球和太阳的引力相互作用(潮汐)导致整个地球的周期性形变，其影响可与大地震的影响相媲美。类似于地震和潮汐引起的微观应变可以在实验室中进行研究，从而也可以研究温度和化学环境对响应的影响。拟议工作的挑战是将实验室结果应用于地震学和大地测量学的全球观测。这种方法的前景是提高我们对地球内部条件及其物理描述的理解。这些发现将对地球表面自上一个冰河时代以来持续的反弹进行建模，影响确定海平面变化的原因，以及对其他行星和卫星的潮汐建模。研究人员建议结合从地震体波(秒)到正常模式(分钟-小时)和潮汐(小时-小时)的大范围时间尺度的小应变变形观测，以确定地球内部能量耗散的频率相关性。这些观测结果将被合并到包含滞弹性的非球形地球的正常模式/潮汐模型中。这个模型的结果将与实验室推导的晶体颗粒及其缺陷的滞弹性行为模型进行比较，这些模型是在实验可访问的参数空间之外进行预测的基础。将实验预测与全球模型进行比较，将有助于限制微物理模型对地震波和潮汐引起的小应变变形的适用性，并最终限制冰川后反弹和(大应变)对流的适用性。同时，正常模式和潮汐信息的结合将对中下地幔的条件和结构产生新的约束，这是通过其他方式难以获得的。

Earthquakes produce sound waves that travel through the interior of the Earth and thereby sample the conditions along their paths. Collections of large numbers of arriving sound waves are used to reconstruct conditions and structure of the interior of the Earth. While traveling through the interior, these waves produce microscopic strains in the rocks they pass through. The response of the rocks to these strains depends on conditions such as temperature and chemical environment. Very large Earthquakes in subduction zones, for example the Andaman-Sumatra earthquake from 2004 or the Alaskan earthquake from 1964, produce enough energy for the Earth to "ring like a bell". Gravitational interaction of the Earth with the Moon and the Sun (tides) causes periodic deformation of the whole Earth that is comparable to the effects of large Earthquakes. Microscopic strains similar to those caused by earthquakes and tides can be investigated in the laboratory, and thereby also the effects of temperature and chemical environment on the response. The challenge of the proposed work is to apply the laboratory results to global observations from seismology and geodesy. The promise of this approach is to improve our understanding of the conditions in the interior of the Earth and its physical description. The findings will have implications for modeling of the ongoing rebound of the surface of the Earth since the last ice age, affecting determination of the causes of changes in sea level, as well as tidal modeling of other planets and moons.The investigators propose to combine observations of small-strain deformation at a broad range of timescales, from seismic body waves (seconds) to normal modes (minutes - hour) and tides (hours to years), to determine the frequency dependence of energy dissipation in the interior of the Earth. These observations will be combined in a normal mode/tidal model of a non-spherical Earth that includes anelasticity. Results from this model will be compared to laboratory-derived models for anelastic behavior of crystalline grains and their defects, which are the basis for predictions outside of the experimentally accessible parameter space. Comparison of experimental predictions with global models will help to constrain the applicability of the microphysical models to small-strain deformation due to seismic waves and tides, and ultimately also post-glacial rebound and (large-strain) convection. At the same time the combination of information from normal modes and tides will yield new constraints on the conditions and structure in the mid to lower mantle, which are difficult to obtain by other means.