A new map of the lava flow field of Nyamulagira (D.R. Congo) from satellite imagery

Smets, B.; Wauthier, C.; d’Oreye, Nicolas

doi:10.1016/j.jafrearsci.2010.07.005

Cited by 59 publications

(91 citation statements)

References 15 publications

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“…Like the lava lake at Erta Ale, the Nyiragongo lava lake also lies at the junction of two rift zones diverging by 20 • , both active historically: one oriented N (1977 and 2002) and one oriented NNW (1977). (2011)(2012) This is Africa's most productive volcano having had over 30 major eruptions in the last 100 years alone (Smets et al, 2010). These eruptions often involved dyke/fissure systems propagating downslope from a caldera above a chamber at ∼3-4 km depth (Toombs and Wadge, 2012;Wauthier et al, 2013) to effusive vents on the flanks.…”

Section: Nyiragongo (2002)mentioning

confidence: 99%

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

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Crustal extension at the East African Rift System (EARS) should, as a tectonic ideal, involve a stress field in which the direction of minimum horizontal stress is perpendicular to the rift. A volcano in such a setting should produce dykes and fissures parallel to the rift. How closely do the volcanoes of the EARS follow this? We answer this question by studying the 21 volcanoes that have erupted historically (since about 1800) and find that 7 match the (approximate) geometrical ideal. At the other 14 volcanoes the orientation of the eruptive fissures/dykes and/or the axes of the host rift segments are oblique to the ideal values. To explain the eruptions at these volcanoes we invoke local (non-plate tectonic) variations of the stress field caused by: crustal heterogeneities and anisotropies (dominated by NW structures in the Protoerozoic basement), transfer zone tectonics at the ends of offset rift segments, gravitational loading by the volcanic edifice (typically those with 1-2 km relief) and magmatic pressure in central reservoirs. We find that the more oblique volcanoes tend to have large edifices, large eruptive volumes, and evolved and mixed magmas capable of explosive behavior. Nine of the volcanoes have calderas of varying ellipticity, 6 of which are large, reservoir-collapse types mainly elongated across rift (e.g., Kone) and 3 are smaller, elongated parallel to the rift and contain active lava lakes (e.g., Erta Ale), suggesting different mechanisms of formation and stress fields. Nyamuragira is the only EARS volcano with enough sufficiently well-documented eruptions to infer its long-term dynamic behavior. Eruptions within 7 km of the volcano are of relatively short duration (<100 days), but eruptions with more distal fissures tend to have lesser obliquity and longer durations, indicating a changing stress field away from the volcano. There were major changes in long-term magma extrusion rates in 1977 (and perhaps in 2002) due to major along-rift dyking events that effectively changed the Nyamuragira stress field and the intrusion/extrusion ratios of eruptions.

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Section: Nyiragongo (2002)mentioning

confidence: 99%

Historical Volcanism and the State of Stress in the East African Rift System

et al. 2016

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“…[8] While Nyamulagira erupts every 2-4 years [Smets et al, 2010a], only two historical eruptions of Nyiragongo have been recorded; in 1977 [Tazieff, 1977] and in 2002 [Komorowski et al, 2002[Komorowski et al, /2003Tedesco et al, 2007]. Nyiragongo is one of the few volcanoes on Earth to host an active lava lake.…”

Section: Geologic Settingmentioning

confidence: 99%

Magma sources involved in the 2002 Nyiragongo eruption, as inferred from an InSAR analysis

Wauthier¹,

Cayol²,

Kervyn³

et al. 2012

J. Geophys. Res.

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along a 20 km-long fracture network extending from the volcano to the city of Goma. The event was captured by InSAR data from the ERS-2 and RADARSAT-1 satellites. A combination of 3D numerical modeling and inversions is used to analyze these displacements. Using Akaike Information Criteria, we determine that a model with two subvertical dikes is the most likely explanation for the 2002 InSAR deformation signal. A first, shallow dike, 2 km high, is associated with the eruptive fissure, and a second, deeper dike, 6 km high and 40 km long, lies about 3 km below the city of Goma. As the deep dike extends laterally for 20 km beneath the gas-rich Lake Kivu, the interaction of magma and dissolved gas should be considered as a significant hazard for future eruptions. A likely scenario for the eruption is that the magma supply to a deep reservoir started ten months before the eruption, as indicated by LP events and tremor. Stress analysis indicates that the deep dike could have triggered the injection of magma from the lake and shallow reservoir into the eruptive dike. The deep dike induced the opening of the southern part of this shallow dike, to which it transmitted magma though a narrow dike. This model is consistent with the geochemical analysis, the lava rheology and the pre-and post-eruptive seismicity. We infer low overpressures (1-10 MPa) for the dikes. These values are consistent with lithostatic crustal stresses close to the dikes and low magma pressure. As a consequence, the dike direction is probably not controlled by stresses but rather by a reduced tensile strength, inherited from previous rift intrusions. The lithostatic stresses indicate that magmatic activity is intense enough to relax tensional stresses associated with the rift extension.

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“…As outlined by Carn and Bluth (2003) the link between sulphur emissions and erupted lava is an important tool for hazard assessment and "it would be interesting to determine information regarding the lava/tephra production" of Nyamuragira eruptions. However, volumetric estimates are currently retrieved from the area of the lava fields and an assumed average thickness (Kasahara 1983;Smets et al 2010, Head et al 2012. Therefore, there is a need for improved measurements of eruption rates at Nyamuragira.…”

Section: Introductionmentioning

confidence: 99%