First recorded eruption of Nabro volcano, Eritrea, 2011

Abstract

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.

The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions

“…Two major lava flows were produced, one of which extended ~ 15 km to the northwest of the volcano; the other was shorter and moved southwards within the caldera Fig. 2; Goitom et al 2015). The tephra field was welldefined to the south-west of the edifice (towards and blanketing Mallahle volcano).…”

“…During the 2011 eruption, activity was concentrated along a rift at 90° to the Bidu Massif (Goitom et al 2015). Two major lava flows were produced, one of which extended ~ 15 km to the northwest of the volcano; the other was shorter and moved southwards within the caldera Fig.…”

“…1), forming part of an alignment known as the Bidu Massif. The volcano was little heard of until 2011 when it was the site of a substantial explosive and effusive eruption-the first in recorded history-that precipitated a significant humanitarian crisis, disrupted aviation and yielded one of the largest sulphur inputs to the atmosphere since the 1991 eruption of Mount Pinatubo (Goitom et al 2015;Theys et al 2013). Here, we present the first detailed petrological and geochemical study of the eruptive products, focusing on the tephra deposits.…”

What causes subsidence following the 2011 eruption at Nabro (Eritrea)?

“…1) erupted on 12 June 2011 with co-eruptive activity extending into July 2011 (Goitom et al 2015). A detailed synthesis of the eruption can be found in Goitom et al (2015).…”

“…1) erupted on 12 June 2011 with co-eruptive activity extending into July 2011 (Goitom et al 2015). A detailed synthesis of the eruption can be found in Goitom et al (2015). A 17.5 km long lava flow was emplaced to the SW of the edifice, and 4.3 Tg of SO 2 was emitted into the atmosphere (Theys et al 2013), one of the largest atmospheric aerosol perturbations since Mt.…”