Rift volcanism: past, present and future

裂谷火山活动：过去、现在和未来

• 批准号: NE/L013509/1
• 负责人: Derek Keir
• 金额: $ 35.93万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FL013509%2F1
• 关键词: Rift; volcanism; past; present; future

Early explorers called it Africa's Great Rift Valley, a narrow strip that runs for thousands of kilometres from Djibouti to Mozambique and is perhaps most famous for the vast herds of the Serengeti, mountain gorillas and dramatic landscapes of high peaks and fertile plains. The mountains and valleys are the signs of a continent slowly tearing apart. Moving apart more slowly than your finger nails grow, the African continent will one day split into two, creating a new ocean. As the Earth's crust stretches and thins - like plasticine when you pull it - rocks melt, and the resulting magma rises to the surface. The resultant eruptions have had a dramatic and varied impact on the landscape: great lakes have filled the holes left by enormous eruptions; eruptions of volcanic glass have created a chain of peaks, and wide fields are filled with scattered cones and lava flows. This volcanic landscape is hazardous - a recent report for the World Bank ranked 49 of Ethiopia's 65 volcanoes in the highest category of hazard uncertainty. The high temperatures associated with magma in the Rift Valley make it a rich source of carbon-neutral geothermal power. Multi-billion dollar investments by development agencies are driving a ten-fold expansion in the geothermal infrastructure in East Africa over the next decade. However, the majority of scientific research has focussed on volcanoes in other tectonic settings, such as Hawaii and Japan, leaving the volcanoes of the East African Rift largely a mystery. For many of them, we can't even say when the last eruption look place and there is no monitoring equipment to detect the early stages of an upcoming eruption. The eruption of Nabro volcano in 2011 was a timely reminder of the potential threats. Situated on the frontier between Ethiopia and Eritrea, the area is remote and sparsely populated, yet the eruption caused 32 fatalities, displaced >5000 people and disrupted regional aviation. Had this eruption originated from one of other 29 volcanoes with the same perceived hazard, but in densely-populated central Ethiopia, the humanitarian and societal cost would have been considerable. RiftVolc will focus on the volcanoes of the Main Ethiopian Rift in central Ethiopia. The aim is to understand their past behaviour, look for subtle signs of present-day activity and assess the threat posed to the infrastructure and people on and around them. RiftVolc will involve scientists from many disciplines working together to produce an integrated view of the past, present and future of the volcanoes in this region and compare it to other parts of East Africa and volcanoes elsewhere. Together we will spend several months out in Ethiopia, collecting samples, mapping the geology and deploying geophysical instruments, before returning to the lab to use analyse the data and create computer models of the results. Petrologists and geochemists will look at the lavas and ash to figure out the timing, size and style of past eruptions. Geophysicists will look for tiny earthquakes, changes in gravity, the passage of electrical currents and movements of the Earth's surface to understand the plumbing system feeding the volcanoes today. Finally, experts in hazard assessment will model possible scenarios and create a long-range eruption forecast for Ethiopia. We will work with our colleagues in the University of Addis Ababa and the Geological Survey of Ethiopia to ensure our findings are appropriate communicated to the government, industry and people of Ethiopia and with international groups such as the Global Volcano Model to communicate our results to development agencies such as the UN and the World Bank.

早期的探险家称它为非洲的大裂谷，这是一条从吉布提到莫桑比克绵延数千公里的狭长地带，可能最著名的是塞伦盖蒂山脉的大量羊群、山地大猩猩以及高山和肥沃平原的壮观景观。山脉和山谷是这块大陆正在慢慢分裂的迹象。非洲大陆的分裂速度比你的指甲长得还慢，总有一天非洲大陆会一分为二，形成一个新的海洋。随着地壳的伸展和变薄，当你拉它的时候，岩石融化，由此产生的岩浆上升到地表。由此产生的喷发对景观产生了戏剧性和多种多样的影响：大湖填满了巨大喷发留下的洞穴；火山玻璃喷发形成了一连串的山峰；广阔的田野充满了分散的圆锥体和熔岩流。这种火山景观是危险的--世界银行最近的一份报告将埃塞俄比亚65座火山中的49座列入了最高危险不确定性类别。裂谷与岩浆相关的高温使其成为碳中性地热能的丰富来源。发展机构的数十亿美元投资正在推动东非地热基础设施在未来十年扩大十倍。然而，大多数科学研究都集中在其他构造环境中的火山，如夏威夷和日本，这使得东非裂谷的火山在很大程度上是一个谜。对于他们中的许多人来说，我们甚至不能说出最后一次喷发的位置，也没有监测设备来检测即将到来的喷发的早期阶段。2011年纳布罗火山的喷发及时提醒人们注意潜在的威胁。该地区地处埃塞俄比亚和厄立特里亚边境，地处偏远，人口稀少，但火山喷发造成32人死亡，5000人流离失所，并扰乱了地区航空。如果这次喷发来自其他29座具有同样危险的火山中的一座，但在人口稠密的埃塞俄比亚中部，人道主义和社会代价将是相当大的。RiftVolc将重点关注埃塞俄比亚中部主要埃塞俄比亚裂谷的火山。目的是了解他们过去的行为，寻找当今活动的微妙迹象，并评估对基础设施和基础设施上及其周围的人构成的威胁。RiftVolc将让来自多个学科的科学家共同努力，对该地区火山的过去、现在和未来产生一个综合的看法，并将其与东非其他地区和其他地方的火山进行比较。我们将一起在埃塞俄比亚呆上几个月，收集样本，绘制地质图，部署地球物理仪器，然后返回实验室使用分析数据并创建结果的计算机模型。岩石学家和地球化学家将研究熔岩和火山灰，以确定过去喷发的时间、大小和风格。地球物理学家将研究微小的地震、重力的变化、电流的通道和地球表面的运动，以了解今天为火山提供燃料的管道系统。最后，危险评估专家将对可能的情景进行建模，并对埃塞俄比亚进行长期喷发预测。我们将与亚的斯亚贝巴大学和埃塞俄比亚地质调查局的同事合作，确保我们的发现适当地传达给埃塞俄比亚政府、行业和人民，并与全球火山模型等国际组织合作，将我们的结果传达给联合国和世界银行等发展机构。

项目成果

Crustal structure of the Gulf of Aden southern margin: Evidence from receiver functions on Socotra Island (Yemen)

• DOI: 10.1016/j.tecto.2014.10.014
• 发表时间: 2014-12-10
• 期刊: TECTONOPHYSICS
• 影响因子: 2.9
• 作者: Ahmed, Abdulhakim;Leroy, Sylvie;Obrebski, Mathias
• 通讯作者: Obrebski, Mathias

Using Ambient Noise to Image the Northern East African Rift

• DOI: 10.1029/2018gc008129
• 发表时间: 2019-04-01
• 期刊: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
• 影响因子: 3.5
• 作者: Chambers, Emma L.;Harmon, Nicholas;Rychert, Catherine A.
• 通讯作者: Rychert, Catherine A.

A multidisciplinary study of the final episode of the Manda Hararo dyke sequence, Ethiopia, and implications for trends in volcanism during the rifting cycle

• DOI: 10.1144/sp420.6
• 发表时间: 2015-05
• 期刊: Special Publications
• 作者: T. Barnie;D. Keir;I. Hamling;B. Hofmann;M. Belachew;Simon Carn;David Eastwell;Jos Hammond;A. Ayele;Clive Oppenheimer;Tim J. Wright

Seismicity of the central Afar rift and implications for Tendaho dam hazards

• DOI: 10.1144/sp420.9
• 发表时间: 2015-06
• 期刊: Special Publications
• 作者: A. Ayele;C. Ebinger;Carolyn van Alstyne;D. Keir;C. Nixon;M. Belachew;J. Hammond

Variations in melt emplacement beneath the northern East African Rift from radial anisotropy

• DOI: 10.1016/j.epsl.2021.117150
• 发表时间: 2021-09-01
• 期刊: EARTH AND PLANETARY SCIENCE LETTERS
• 影响因子: 5.3
• 作者: Chambers, Emma L.;Harmon, Nicholas;Keir, Derek
• 通讯作者: Keir, Derek