Investigation of the influence of mantle structures on Earth's core observations

研究地幔结构对地心观测的影响

• 批准号: 365859872
• 负责人: Professorin Dr. Christine Thomas
• 金额: --
• 依托单位: Institut für Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/365859872?language=en
• 关键词: Investigation; influence; mantle; structures; Earth

Seismic investigations of the Earth's core are often carried out using body waves and the waves PKP and SKS are of great importance here. Usually the assumption is made that the paths of the waves are similar in the mantle and that mantle structures can be neglected when analysing core phases. However, his assumption does not have to be correct and the aim of this proposal is to quantify how mantle structures can influence seismic core phases. For this we are planning to use array seismological methods for five paths and measure path deviations (slowness and backazimuth) of the seismic waves, which ultimately lead to travel time deviations. If the path deviations are neglected, the resulting travel time differences will be projected into the core and this can lead to mis-leading models if the inner core. The use of converted waves (SKP and PKS), which have a different path on part of the mantle path, in combination with PKP waves allow the differential investigation of mantle and core structures. In addition to the array observations, seismic 3D modeling will show the extent to which the paths and travel times of the seismic waves are influenced by high-resolution seismic velocity models (tomography) and which structures in the mantle and core generate path and travel time deviations those waves used in our study. Furthermore, using 3D modeling we aim to make predictions for different paths that can be used for future core investigations. The results of this study have an influence not only on seismological models but also on geodynamic and mineralogical investigations, since travel time variations have been used to constrain core anisotropy. By using PKP and SKS waves, which pass through the same regions in the mantle, structures of the lowermost mantle can also be better quantified, since the different effect of structures on S-waves and P-waves can provide information about deep Earth mineralogy.

地核的地震调查通常使用体波进行，PKP波和SKS波在这里非常重要。通常假设地震波在地幔中的路径是相似的，在分析地核相时可以忽略地幔结构。然而，他的假设并不一定是正确的，这个建议的目的是量化地幔结构如何影响地震岩心相位。为此，我们计划使用阵列地震学方法对五个路径进行测量，并测量地震波的路径偏差（慢度和反方位角），最终导致传播时间偏差。如果忽略路径偏差，则由此产生的走时差将被投影到核心中，这可能导致错误的模型。转换波（SKP和PKS）在部分地幔路径上具有不同的路径，结合PKP波可以对地幔和地核结构进行区分研究。除了阵列观测之外，地震3D建模将显示地震波的路径和传播时间受到高分辨率地震速度模型（断层扫描）的影响程度，以及地幔和岩心中的哪些结构产生了我们研究中使用的地震波的路径和传播时间偏差。此外，利用3D建模，我们的目标是预测不同的路径，可用于未来的岩心研究。这项研究的结果不仅对地震模型有影响，而且对地球动力学和矿物学调查也有影响，因为走时变化被用来限制岩心的各向异性。由于构造对横波和纵波的不同影响可以提供深部地球矿物学信息，因此利用穿过地幔同一区域的PKP和SKS波也可以更好地量化最下层地幔的结构。