We present a synthesis of diverse observations of the first recorded eruption of Nabro volcano, Eritrea, which began on 12 June 2011. While no monitoring of the volcano was in effect at the time, it has been possible to reconstruct the nature and evolution of the eruption through analysis of regional seismological and infrasound data and satellite remote sensing data, supplemented by petrological analysis of erupted products and brief field surveys. The event is notable for the comparative rarity of recorded historical eruptions in the region and of caldera systems in general, for the prodigious quantity of SO2 emitted into the atmosphere and the significant human impacts that ensued notwithstanding the low population density of the Afar region. It is also relevant in understanding the broader magmatic and tectonic significance of the volcanic massif of which Nabro forms a part and which strikes obliquely to the principal rifting directions in the Red Sea and northern Afar. The whole-rock compositions of the erupted lavas and tephra range from trachybasaltic to trachybasaltic andesite, and crystal-hosted melt inclusions contain up to 3,000 ppm of sulphur by weight. The eruption was preceded by significant seismicity, detected by regional networks of sensors and accompanied by sustained tremor. Substantial infrasound was recorded at distances of hundreds to thousands of kilometres from the vent, beginning at the onset of the eruption and continuing for weeks. Analysis of ground deformation suggests the eruption was fed by a shallow, NW–SE-trending dike, which is consistent with field and satellite observations of vent distributions. Despite lack of prior planning and preparedness for volcanic events in the country, rapid coordination of the emergency response mitigated the human costs of the eruption.

中文翻译：

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2011 年厄立特里亚纳布罗火山首次记录喷发

我们综合了对 2011 年 6 月 12 日开始的厄立特里亚纳布罗火山首次记录喷发的各种观察结果。虽然当时没有对火山进行监测，但已经有可能重建火山的性质和演化。通过对区域地震和次声数据以及卫星遥感数据的分析，辅以对喷发产物的岩石学分析和简短的实地调查来进行喷发。该事件的显着特点是该地区和火山口系统记录的历史喷发相对罕见，排放到大气中的二氧化硫数量惊人，尽管阿法尔地区人口密度低，但随之而来的重大人类影响。它还与理解火山地块更广泛的岩浆和构造意义有关，纳布罗是其中的一部分，它倾斜于红海和阿法尔北部的主要裂谷方向。喷发的熔岩和火山灰的全岩成分范围从粗玄武岩到粗玄武岩安山岩，以晶体为主体的熔体包裹体含有高达 3,000 ppm 的硫（按重量计）。喷发之前发生了明显的地震活动，由区域传感器网络检测到，并伴随着持续的震颤。在距火山口数百至数千公里的地方记录到大量次声，从喷发开始并持续数周。对地面变形的分析表明喷发是由一个浅的、NW-SE 向的堤坝推动的，这与现场和卫星观测的喷口分布一致。尽管该国缺乏针对火山事件的事先规划和准备，但应急响应的快速协调减轻了火山喷发的人员成本。