Seismic heterogeneities beneath the Atlantic and Africa - thermal or chemical?

我们正计划研究南大西洋和非洲下面的S地幔的地震结构，与断层图像中可以看到的大的低速剪切波异常有关。利用阵列地震学和偏移方法，从地震波场中提取尽可能多的信息，试图确定大横波异常是热成因还是化学成因。在非洲永久和临时台阵记录的南美洲和南桑威奇群岛的事件将特别照亮南大西洋下方大剪切速度异常的边缘。搜索地震结构，利用差异结构(一个事件提供了几个深度的结构信息)和波形、频率等信息，我们可以确定异常的程度和观测到的地震结构的物理参数。采用地球动力学研究的输入和矿物物理参数的地震模拟结果将与观测地震数据进行比较，然后以与观测数据相同的方式分析合成数据。利用所有信息，我们可以检验关于异常起源的不同假设。

We are planning to investigate seismic structures in the Earth s mantle beneath the South Atlantic and Africa, associated with the large low velocity shear wave anomaly that can be seen in tomographic images. Using array seismology and migration and extracting as much information as possible from the seismic wavefield, we will try to determine, whether the large shear wave anomaly has a thermal or chemical origin. Events in South America and South Sandwich Islands recorded at permanent and temporary arrays in Africa will especially illuminate the edge of the large shear velocity anomaly beneath the South Atlantic. Searching for seismic structures and using differential structures (one event gives information on structures in several depths) and information on waveforms, frequencies etc, we can determine the extent of the anomaly and the physical parameters of the observed seismic structures. Seismic modeling results with inputs from geodynamic studies and mineral physical parameters will be compared to the observed seismic data after analysing the synthetic data in the same way as the observations. Using all information, we can test the different hypotheses regarding the origin of the anomaly.