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

大陆裂谷作用是板块构造旋回的基本组成部分，是地热和矿产资源、地震和火山灾害以及地球物理研究的纽带。世界范围内裂谷带之间的巨大变化表明，大陆分裂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，从火山和地震的高度延伸的裂谷中心到裂谷的侧翼，在那里伸展刚刚开始，裂谷前结构仍然很明显。东非裂谷的埃塞俄比亚主裂谷可能是世界上最具代表性的大陆裂谷。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，并为在地球科学领域代表性不足的早期职业研究人员提供职业机会。整个裂谷系统内部结构的详细成像，从侧面到轴，可以揭示埃塞俄比亚主裂谷伸展过程的力学、控制和时间依赖性。最近从宽孔径宽带地震阵列中获得的数据对于对可能控制裂谷动力学的预裂构造进行采样以及对裂谷轴和侧翼之间的关键地球动力学过渡带进行成像至关重要。我们的层析技术需要在贝叶斯框架内同时反演P和S接收函数与瑞利波相速度；这种方法非常适合于捕捉岩性/地震不连续面、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体轨迹以及该裂谷的时间积分应变史。该项目利用了该地区以前许多项目的地震数据，结合了多个部署的优势，以获得一个概括性的理解。与埃塞俄比亚科学家的合作以及支持代表性不足的研究人员的早期职业生涯是这个项目更广泛的影响之一。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.