Whole Mantle Structures from Broadband Modeling

宽带建模的整个地幔结构

• 批准号: 9814908
• 负责人: Donald Helmberger
• 金额: $ 16.9万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-15 至 2001-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814908&HistoricalAwards=false
• 关键词: Whole; Mantle; Structures; Broadband; Modeling

9814908HelmbergerThis research involves the utilization of revolutionary improvements in seismic data, due to the Global Seismic Network and PASSCAL portable seismometer campaigns, in order to resolve mantle structure by means of body wave and surface wave techniques. Considerable progress has been made in mapping out lateral variations in seismic velocity in the mantle, demonstrating the active dynamic processes going on beneath the earth's surface. This research combines long-period surface wave inversion, travel-time tomographic imaging, and detailed whole record modeling. An intercomparison of models independently derived from these varied techniques involving totally different data sets show great complexity but, fortunately, some agreement. The major goal is to reconcile disagreements where resolvable. The major issues to be addressed are upper-mantle heterogeneity and its extension into the transition region (down to 670 km) and connections to lower mantle structures. The long-wavelength circum-Pacific down-willing region needs to be localized into more discrete continuous seismic structures with reliable estimates of P and S anomalies and their sharpness. Zones of slab buckling and abrupt thickening that are so abundant in dynamic models should be identifiable seismically. Similarly, the large-scale slow structures beneath Africa and mid-Pacific, although well established near the CMB, are less well defined at shallower depths where models vary greatly. The results are important as input to geochemical, mineral physical, and geodynamic models of the earth.

9814908 Helmberg这项研究涉及利用由于全球地震网络和PASSCAL便携式地震仪活动而在地震数据方面取得的革命性改进，以便通过体波和表面波技术解决地幔结构。 在绘制地幔中地震速度横向变化图方面取得了相当大的进展，显示了地球表面之下正在进行的活跃的动力学过程。 这项研究结合了长周期面波反演、走时层析成像和详细的全记录建模。 从这些不同的技术，涉及完全不同的数据集独立得出的模型的相互比较显示出很大的复杂性，但幸运的是，一些协议。 主要目标是在可以解决的地方调和分歧。 要解决的主要问题是上地幔的不均匀性及其向过渡区的延伸（下至670公里）以及与下地幔结构的联系。 长波长的环太平洋向下的区域需要本地化到更离散的连续地震结构与可靠的估计P和S异常及其锐度。 在动力模型中大量存在的板屈曲和突然增厚的区域应该是地震学上可以识别的。 同样，非洲和中太平洋下方的大规模缓慢结构，虽然在CMB附近已经很好地建立，但在模型差异很大的较浅深度处，则不太清楚。 研究结果对地球化学、矿物物理和地球动力学模型的建立具有重要意义。