Constraining Two Prominent Low-Velocity Anomalies in the Lower Mantle beneath Africa and Pacific

研究者提出绘制非洲和太平洋下地幔两个显著低速异常的详细结构和速度特征。 他将通过二维混合方法使用广泛的波形建模来约束地震速度、几何形状和使用各种地震相位的不同方向的地震异常的长度尺度。 PI还建议沿着本研究计划的过程开发三维混合地震代码。将使用三维混合程序来正演验证从二维混合方法波形模拟获得的地震结果的有效性。该建议的智力价值包括地震学的观测和理论方面。该提案的观测方面包括收集、识别、解释高质量异常地震数据并建立模型，其科学目标是绘制下地幔两个显著低速异常的详细特征。该提案的理论方面包括系统研究地震波在非均匀地幔中的传播，对异常地震数据进行详细建模，以及开发3D混合方法。 该研究对进一步认识地球的形成和演化、地幔热化学对流、核幔边界的性质以及“DUPAL异常”等地球化学油气藏的成因具有重要意义。 新的3D代码将在地震学界有广泛的应用。

WenThe investigator proposes to map out detailed structural and velocity features of the two prominent low-velocity anomalies in the lower mantle beneath Africa and the Pacific. He will use extensive waveform modeling by the 2D hybrid methods to constrain the seismic velocities, geometry, and length-scale of the seismic anomalies from various directions using various seismic phases. The PI also proposes to develop a three-dimensional hybrid seismic code along the course of this research program. The three-dimensional hybrid code will be used to forward verify the validity of the seismic results obtained from the 2D-hybrid method waveform modeling. The intellectual merits of the proposal include both observational and theoretical aspects of seismology. The observational aspect of the proposal includes collection, identification, interpretation and modeling of high-quality anomalous seismic data, with a scientific goal of mapping detailed features of the two prominent low-velocity anomalies in the lower mantle. The theoretical aspect of the proposal includes systematic studies of seismic wave propagation in a heterogeneous mantle, detailed modeling of the anomalous seismic data, and the development of a 3D hybrid method. The proposed research has broad impacts on our further understanding of the formation and evolution of the Earth, thermal-chemical convection in the mantle, the nature of the core-mantle boundary, and the origin of some geochemical reservoirs, such as "the DUPAL anomaly". The new 3D code will have broad applications in the seismology community.