Collaborative Research: A community velocity field for East Africa

非洲沿东非裂谷系统的解体长期以来一直是稳定大陆在构造旋回中解体的典型例子。因此，许多地球物理和地质研究对很长的裂谷系统的不同部分进行了详细的测量和分析，包括利用全球定位系统大地测量来测量非洲大部分地区(努比亚)与其东部(索马里)持续分离的速度、方向和空间分布。然而，这些先前的研究很少(如果有的话)全面地看待整个裂谷和大陆，以探索裂谷的不同部分如何联系在一起，相互作用，或影响裂谷以外的大陆邻近部分。这种全面的观点对于更好地了解整个大陆，以及其他大陆过去或未来将如何分裂是必要的。广泛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。本实验解决了建立这样一个大陆尺度的裂谷观点的两个任务。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进行的所有已知大地测量观测。然后，这些数据将被合并到单个大尺度速度场中，从而最大限度地减少因参考框架定义、处理策略或网络几何形状的变化而引起的相对速度(和应变率)的任何不确定性。其次，它包括对过去测量历史有限或很差的高价值遗址进行重新测量，包括一个横跨肯尼亚-埃塞俄比亚交界处图尔卡纳凹陷的运动网络，肯尼亚的两个平行活动的裂谷构造与埃塞俄比亚的一个裂谷相连。这两项努力都是为了在大陆范围内为整个非洲裂谷系统提供尽可能高质量的现代构造速度场，作为一项基础研究成果，并作为针对非洲系统和整个裂谷的许多其他不同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.