Collaborative Research: A community velocity field for East Africa

非洲沿着东非裂谷系的分裂一直是稳定大陆在构造周期中分裂的典型例子。 因此，许多地球物理和地质研究已经详细测量和分析了非常长的裂谷系统的不同部分，包括使用GPS大地测量来测量非洲大部分地区（努比亚）从其东部（索马里）分离的速度，方向和空间分布的研究。 然而，这些先前的研究很少（如果有的话）对整个裂谷和大陆进行全面的观察，以探索裂谷的不同部分如何连接在一起，相互作用，或影响裂谷以外的大陆邻近地区。 这种全面的观点对于更好地了解整个大陆以及其他大陆过去如何分裂或将来如何分裂是必要的。 大范围的裂谷过程构成了板块构造理论的基础，也影响了地震、火山、地热资源、矿产资源和地形在时间和空间上的分布。本实验解决了构建大陆尺度裂谷观的两个任务。 首先，它包括汇编来自代表10个国家的22个不同研究小组在非洲和周边地区的所有已知大地测量观测。 然后，这些数据将被组合成一个单一的大规模速度场，从而最大限度地减少任何不确定性的相对速度（和应变率）所产生的变化，在参考框架的定义，处理策略，或网络的几何形状。 其次，它包括对过去测量历史有限或较差的高价值地点进行重新测量，包括跨越肯尼亚-埃塞俄比亚边境图尔卡纳洼地的运动网络，其中肯尼亚的两个平行活动裂谷结构与埃塞俄比亚的一个裂谷相连。 这两项工作的目的都是在大陆尺度上为整个非洲裂谷系提供尽可能高质量的现今构造速度场，作为基础研究产品，并作为针对非洲裂谷系和裂谷作用的许多其他各种研究工作的开放式运动学框架。

The break-up of Africa along the East African Rift System has long served as the type example of how stable continents fall apart in tectonic cycles. As a result, many geophysical and geologic studies have measured and analyzed different sections of the very long rift system in detail, including studies using GPS geodesy to measure the speed, direction, and distribution in space of the ongoing separation of most of Africa (Nubia) from its eastern part (Somalia). However, few, if any, of these previous studies took a comprehensive view over the whole rift and continent, in order to explore how different sections of the rift link together, interact with one another, or influence neighboring parts of the continent outside of the rift valleys. Such a comprehensive view is necessary to better understand the whole continent and, indeed, how other continents split apart in the past or will in the future. The broad process of rifting forms the basis of plate tectonic theory, and also influences the distribution of earthquakes, volcanoes, geothermal resources, mineral resources, and topography in both time and space.This experiment addresses two pieces of the task of building such a continent-scale view of rifting. First, it includes compiling all known geodetic observations in Africa and surrounding regions from 22 different research groups representing 10 countries. These data will then be combined into a single large-scale velocity field, thus minimizing any uncertainties in relative velocities (and strain rates) arising from variations in reference frame definitions, processing strategies, or network geometries. Second, it includes re-measurements of high-value sites with limited or poor past measurement histories, including a campaign network spanning the Turkana Depression of the Kenya-Ethiopia borderlands, where two parallel active rift structures in Kenya relay to a single rift in Ethiopia. Both of these efforts are directed at providing the highest possible quality present-day tectonic velocity field for the whole African Rift System at the continent scale, as a basic research product and as an open-access kinematic framework for many other diverse research efforts directed at the African system and rifting in general.