Physics of Seismic and Tidal Attenuation

地震和潮汐衰减物理学

• 批准号: RGPIN-2016-05408
• 负责人: Morozov, Igor
• 金额: $ 1.75万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633630
• 关键词: Physics; Seismic; Tidal; Attenuation

The theory of elasticity and internal friction in Earth’s materials is most important for seismology, materials science, and studies of terrestrial and planetary tides. We argue that despite its long and broad use, the conventional viscoelastic model is insufficient for two reasons. First, this model is based on postulated mathematical concepts such as the creep function, quality factors (Q), time-dependent moduli, and the correspondence principle which lack explanations from first-principle physical laws. Second, this model is insufficiently general, and inelasticity within the heterogeneous Earth does not always reduce to an effect of a Q. For example, in rocks containing pore fluids (the primary cause of seismic attenuation in sedimentary rocks), secondary P-waves are always present. These secondary waves contribute to all observable phenomena, such as wave velocity dispersion, reflection amplitudes in layered media or strain/stress phase lags in laboratory measurements. Nevertheless, secondary wave modes are not included in the viscoelastic model, which only considers the Q factors for the primary modes.

地球材料的弹性和内耗理论对地震学、材料科学以及地球和行星潮汐的研究是最重要的。我们认为，尽管传统的粘弹性模型有着长期而广泛的使用，但由于两个原因，它是不够的。首先，该模型基于假设的数学概念，如蠕变函数、品质因数(Q)、随时间变化的模数和对应原理，这些概念缺乏第一原理物理定律的解释。其次，这个模型不够通用，非均质地球内部的非弹性并不总是减小到Q的影响。例如，在含有孔隙流体的岩石中(沉积岩中地震衰减的主要原因)，次要P波总是存在的。这些二次波对所有可观察到的现象都有贡献，例如波速频散、层状介质中的反射幅度或实验室测量中的应变/应力相位滞后。而粘弹性模型只考虑了主振型的Q因子，没有考虑二次波振型。