Mechanisms and implications of the 2011 eruption of Nabro volcano, Eritrea

厄立特里亚纳布罗火山的喷发具有很大的科学价值，甚至在它所在的阿法尔偏远地区也产生了重大影响。它位于阿法尔伸展带，但就在达纳基尔阿尔卑斯山中生代地壳块体的南面。它是一座以粗面岩为主的建筑物，有一个直径8公里的火山口和伴生的火成岩。这是纳布罗火山有记录以来的第一次喷发，突显了火山口系统在没有预警的情况下喷发的可能性。这也是在裂谷的这一特定部分首次记录到的地震活动。对这种构造背景下的岩浆分异、储运机制和喷发过程知之甚少。这种紧迫性反映了在熔岩和气体排放停止之前到达现场的希望，同时地震活动率仍然很高，并希望采样未受干扰的火山灰和熔岩。我们是唯一一个被邀请参观和研究喷发现场的国际团体。现场数据将补充卫星对变形和气体排放的观测。火山喷发造成7人死亡，5000人流离失所，需要持续的人道主义反应。火山灰云扰乱了航空，大大增加了图卢兹火山灰咨询中心的工作，该中心也在追踪南部非洲上空的普耶霍羽流。根据卫星观测，这次喷发是在世界协调时6月12日20时42分之前，在强烈地震活动之后不久开始的。这次喷发是通过吉布提的次声记录探测到的，自1991年皮纳图博喷发以来(根据臭氧监测仪器的数据检索，释放出约2Tg的SO2)(在编写本报告时，SO2的排放仍在继续)已经是大气中SO2的最大来源之一。该项目的主要目的是对喷发的性质和原因进行详细的综合，在了解世界各地不安的火山口的背景下评估事件，并将纳布罗的活动与作为NERC Afar Consortium(http://www.see.leeds.ac.uk/afar/).)研究重点的裂隙玄武岩系统进行比较和对比

The eruption of Nabro in Eritrea is of great scientific interest and has had substantial impacts even in the remote part of Afar in which it is located. It is sited in the extensional zone of Afar, but just south of the Mesozoic crustal block of the Danakil Alps. It is a predominantly trachytic edifice, with an 8-km-diameter caldera and associated ignimbrites. This is the first eruption of Nabro on record, highlighting the potential of caldera systems to erupt without warning. It is also the first seismicity of note recorded in this particular part of the rift. Comparatively little is known about magma differentiation, storage and transport mechanisms and eruptive processes in such tectonic settings. The urgency reflects the hope of reaching the site before cessation of lava and gas emissions, while seismicity rates remain high, and to sample undisturbed tephra and lavas. We are the only international group to be invited to visit and study the eruption site. The field data will complement satellite observations of deformation and gas emission. The eruption resulted in seven fatalities and has displaced 5000 people, requiring an ongoing humanitarian response. Aviation was disrupted by ash clouds, adding considerably to work of the Toulouse Volcanic Ash Advisory Centre, which was also tracking the Puyehue plume above southern Africa. Based on satellite observations, the eruption began shortly before 20:42 UTC on 12 June following intense seismicity. The eruption was detected via infrasound records in Djibouti, and already (emissions continue at the time of writing) ranks among the largest sources of SO2 to the atmosphere since the 1991 Pinatubo eruption (~2 Tg of SO2 released according to retrievals of Ozone Monitoring Instrument data). The main aims of the project are to arrive at a detailed synthesis of the nature and causes of the eruption, to evaluate the events in the context of understanding restless calderas worldwide, and to compare and contrast activity of Nabro with the fissural basaltic systems that have been the focus of research by the NERC Afar Consortium (http://www.see.leeds.ac.uk/afar/).