Photographer's Note

Nyiragongo at night

The silica-undersaturated Nyiragongo volcanics, located in the East African Rift, have globally unique chemical compositions and unusually low viscosities, only higher than carbonatite lavas, for terrestrial silicate magmas.

In January 2002, Nyiragongo volcano erupted about 20 million m3 of lava from fractures on its southern flanks. The nearby city of Goma was inundated by two lava flows, which caused substantial socioeconomic disruption and forced the mass exodus of the population, leaving nearly 120,000 people homeless. Field observations showed marked differences between the lava erupted from the northern portion of the fracture system and that later erupted from the southern part.

The Nyiragongo volcano is a stratovolcano composed of a central cone of 1.3 km of diameter at 3470 m above the sea level and two secondary cones on the south and the northeast flanks, namely the Shaheru (2800 m) and Baruta (3200 m), respectively

Nyiragongo with geographical coordinates 1°31’S and 29°15’ E is a stratovolcano belonging to the Virunga volcanic region located just at the northern end of lake Kivu (1460 m). The eruptive activity of the Nyiragongo volcano is related to Hawaiian type, dominated by effusive and passive emission of low viscosity lava at high temperature. The low viscosity is due to its basaltic composition with high content of silicate, so the lava flows generated have high speed.

The long-lived lava lake activities were confined to the following five volcanoes in the world: Mt. Erebus, Kilauea, Erta Ale, Nyiragongo and Nyamulagira. The lava lake in the summit of Nyiragongo was formed probably in the period from1928 til 1977. It came back after the 2002 eruption. It is quite nice to see at night. The lake is about 220 m in diameter.

Since its discovery in 1894, Nyiragongo volcano is well known for its persistent lava lake activity that has fascinated scientists from all over the world. The volcano is also noted for its foiditic magma composition, which produces extremely fluid lava flows, capable of descending the crater flanks at speeds of up to 100 km per hour.

This picture has been published in: Detay M. — Le Nyiragongo : volcan de tous les dangers et maîtrise des risques, in LAVE, revue de l’association de volcanologie européenne, 153, 16-29 (2011).

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Additional Photos by Michel Detay (mdetay) Gold Star Critiquer/Gold Note Writer [C: 487 W: 1 N: 1045] (4929)
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