Collaborative Research: The context for rifting in East Africa - melt distribution and lithospheric removal imaged from axis to flank

大陆裂谷是板块构造旋回的基本组成部分，位于地热和矿产资源、地震和火山灾害以及地球物理研究的交汇点。世界各地裂谷带之间的巨大差异表明，大陆裂解是由构造力和地质特征的复杂相互作用决定的。因此，了解裂谷系统的完整背景是至关重要的，从火山和地震所在的高度伸展的裂谷中心到裂谷侧翼，那里的伸展才刚刚开始，裂谷前的结构仍然明显。东非裂谷的主要埃塞俄比亚裂谷段可能是世界上最具标志性的大陆裂谷。新的成像技术将应用于最近获得的跨越该裂谷的地震数据，以揭示该裂谷的三维内部结构，并阐明该裂谷和世界各地其他裂谷的关键地质过程。该项目涉及与埃塞俄比亚科学家的合作，并为在地球科学中任职人数不足的早期职业研究人员提供了职业机会。对整个裂谷系统从侧面到轴线的内部结构的详细成像，可以揭示埃塞俄比亚主要裂谷中伸展过程的力学、控制和时间相关性。最近从宽口径宽带地震台阵获得的数据对于采样可能控制裂谷动力学的前裂隙构造以及成像裂缝轴和侧翼之间的地球动力学关键过渡区至关重要。我们的层析成像技术需要在贝叶斯框架内用瑞雷波相速度同时反演P和S接收函数；这种方法非常适合于捕捉岩性/地震不连续性、熔体的存在和复杂的三维裂谷结构。各向异性体波反演和分裂研究将有助于约束熔融轨迹以及该裂谷的时间积分应变历史。该项目利用了该地区以前许多项目的地震数据，结合了多次部署的优势，以实现概括性的理解。与埃塞俄比亚科学家的合作和支持代表性不足的研究人员的早期职业生涯是该项目的更广泛影响之一。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Continental rifting is a fundamental part of the plate tectonic cycle, and lies at the nexus of geothermal and mineral resources, seismic and volcanic hazards, and geophysical research. Substantial variation between rift zones worldwide indicates that continental breakup is dictated by a complex interplay of tectonic forces and geologic characteristics. Therefore, it is critical to understand the full context for a rifting system, from the highly extended rift center that houses volcanoes and earthquakes to the flanks of the rift, where extension is just beginning and pre-rift structures are still evident. The Main Ethiopian Rift segment of the East Africa rift is perhaps the world's most iconic continental rift. New imaging techniques will be applied to recently acquired seismic data spanning this rift to reveal the 3-D internal structure of this rift and shed light on key geologic processes in this and other rifts around the world. This project involves collaboration with scientists from Ethiopia and provides career opportunities for early career researchers under-represented in the Earth sciences. Detailed imaging of the internal structure of an entire rift system, from flank to axis, can shed light on the mechanics, controls, and time-dependency of extensional processes in the Main Ethiopian Rift. Recently acquired data from a wide aperture broadband seismic array is critical in sampling pre-rifted structure that may control rift dynamics, as well as to image the geodynamically crucial transitional zone between rift axis and flank. Our tomographic technique entails simultaneous inversion of P and S receiver functions with Rayleigh wave phase velocities within a Bayesian framework; this approach is ideally suited to capture lithologic/seismic discontinuities, the presence of melt, and complex 3-D rift structure. Anisotropic body wave inversions and splitting studies will help constrain the locus of melt as well as the time-integrated strain history of this rift. This project utilizes seismic data from a number of previous projects in the region, combining the strengths of multiple deployments to achieve a synoptic understanding. Collaboration with Ethiopian scientists and supporting the early careers of under-represented researchers are among the broader impacts of this project.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.