Urgent deployment of GPS in Afar (Ethiopia): determining the rheology of incipient oceanic lithosphere

在阿法尔（埃塞俄比亚）紧急部署 GPS：确定早期海洋岩石圈的流变学

• 批准号: NE/D01039X/2
• 负责人: Timothy Wright
• 金额: $ 2.39万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FD01039X%2F2
• 关键词: Urgent; deployment; GPS; Afar; Ethiopia

When tectonic plates move apart, new oceanic crust is eventually formed. This crust grows episodically (every few hundred years or so for any given segment) by the intrusion of magma along vertical cracks (dykes) at mid-ocean ridges. Most of the world's oceanic crust is under several kilometres of water where it is impossible to directly observe the dyke intrusion process. On the 14 September a dyke intrusion event began on land at the northern end of the East African Rift system, in Afar (Ethiopia) - where continental crust has just been stretched sufficiently for 'oceanic' crust to be formed. A 60 km long segment of the rift opened by as much as 9 m, and more than 2 cubic kilometres of magma was intruded. There were many 10s of earthquakes and eruptions from long, open fissures at the surface, blanketed a wide area in ash, displacing some 25,000 pastoralists and their livestock. This is the first major dyke intrusion event on land since the 1970s, and the first to occur in the era of precision space-based measuring techniques. As well as wishing to understand the likelihood of any future activity, the event sets up a simple natural experiment that will help us understand the properties of the earth's outer layers. In essence, the intrusion has given the earth a sudden kick. Measuring how it responds to that kick tells us about how the rocks at depth behave. In particular, we are interested in whether we can see those rocks flow in response to the stress of the kick, and how quickly they flow. We plan to install GPS instruments on the ground that will monitor the movement of the crust continuously, and to use satellite radar images to get snapshots of the deformation. From the combination of these measurements, we will be able to learn about the processes by which continents split apart and oceanic plates grow.

当构造板块分开时，最终形成新的洋壳。由于岩浆沿着大洋中脊的垂直裂缝（堤坝）侵入，地壳会间歇性地生长（对于任何给定的部分，每隔几百年左右）。世界上大部分洋壳都位于数公里深的水下，无法直接观察堤坝侵入过程。 9 月 14 日，在东非裂谷系统北端阿法尔（埃塞俄比亚）的陆地上发生了堤坝入侵事件，这里的大陆地壳刚刚被充分拉伸，足以形成“海洋”地壳。一段60公里长的裂谷裂口达9m，有超过2立方公里的岩浆侵入。地表长而开放的裂缝发生了数十次地震和火山喷发，火山灰覆盖了大片地区，导致约 25,000 名牧民及其牲畜流离失所。这是自 20 世纪 70 年代以来首次发生在陆地上的重大堤坝入侵事件，也是精密天基测量技术时代首次发生的事件。除了希望了解未来任何活动的可能性之外，该活动还设置了一个简单的自然实验，将帮助我们了解地球外层的特性。从本质上讲，这次入侵给地球带来了突然的冲击。测量它对踢击的反应可以告诉我们岩石在深处的行为方式。我们特别感兴趣的是，我们是否可以看到这些岩石因踢力而流动，以及它们流动的速度有多快。我们计划在地面安装GPS仪器，持续监测地壳的运动，并利用卫星雷达图像来获取变形的快照。通过这些测量的结合，我们将能够了解大陆分裂和海洋板块生长的过程。

项目成果

InSAR observations of post-rifting deformation around the Dabbahu rift segment, Afar, Ethiopia

• DOI: 10.1093/gji/ggu003
• 发表时间: 2014-04
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: I. Hamling;T. Wright;É. Calais;E. Lewi;Y. Fukahata

Evidence for focused magmatic accretion at segment centers from lateral dike injections captured beneath the Red Sea rift in Afar

• DOI: 10.1130/g25147a.1
• 发表时间: 2009-01-01
• 期刊: GEOLOGY
• 影响因子: 5.8
• 作者: Keir, Derek;Hamling, Ian J.;Bennati, Laura
• 通讯作者: Bennati, Laura

Geodetic observations of the ongoing Dabbahu rifting episode: new dyke intrusions in 2006 and 2007

对正在进行的达巴胡裂谷事件的大地测量观测：2006 年和 2007 年新的堤坝入侵

• DOI: 10.1111/j.1365-246x.2009.04163.x
• 发表时间: 2009
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Hamling I