报告地点：教学行政楼706会议室
腾讯会议：975-685-212
报告时间：2024-03-08 从15:00到16:30
报告人：苏玉龙（中国科学技术大学）
报告人简介：
苏玉龙，中国科学技术大学博士研究生，2021年本科毕业于中国石油大学（华东）。曾获本科生国家奖学金，山东省优秀毕业生。主要研究方向为利用地震体波震相研究地幔深部结构和核幔边界不均匀性。
报告题目：地幔底部高速异常区域内超低速区的探测及其与俯冲板块的联系
报告内容简介
Ultralow velocity zones revealed by seismological observations at the core–mantle boundary lend clues to the physico-chemical characteristics and dynamic evolution of the Earth’s deep interior. Ultralow velocity zones have been primarily detected within and at the edges of the large low-velocity provinces. Ultralow velocity zones in high-velocity lowermost mantle have also been reported, but global assessment has been limited by data coverage. Here we use geophysical observations of the seismic phase SKKKP and its B-caustic diffractions (SKKKP waves beyond the B-caustic distance) for 60 large and deep-focus events recorded in North America, Europe and China to detect ultralow velocity zones at the core–mantle boundary. We analyse and simulate the extended SKKKP B-caustic diffractions with different velocity anomalies in the mantle and outer core. In addition to ultralow velocity zones around the two large low-velocity provinces beneath the mid-Pacific and Africa, our results support ultralow velocity zones in previously under-explored high-velocity lowermost mantle regions, including Central America, Alaska, Greenland and West and Central Asia. We suggest our evidence for ultralow velocity zones in high-velocity lowermost mantle is consistent with the presence of partially molten subducted oceanic crust at the deep lower mantle.