Barings Bank
Essay by 24 • March 18, 2011 • 825 Words (4 Pages) • 1,435 Views
The volcano of Nyiragongo in East Africa has been active for a long time and has had a major affect on the land as well as the inhabitants around it. Mount Nyiragongo is a volcano in the Virunga Mountains and is part of the Great Rift Valley and is categorized as a type stratovalcano. This volcano is located in The Democratic Republic of the Congo and is also located near the town of Goma and Lake Kivu. The volcano of Nyiragongo is also located west of the border with Rwanda. It partly overlaps two other volcanoes, the Baratu and Shaheru, and is also surrounded by hundreds of small volcanic cinder cones from flank eruptions.
The Virunga Mountains were first determined to be volcanoes in 1891 and out of the eight volcanoes in this mountain range; Nyiragongo and Nyamuragira have together been responsible for forty percent of Africa's historic volcanic eruptions. The volcano of Nyiragongo stretches 11,384 feet tall and the main crater of the volcano is 250 meters deep and 2 kilometers wide. Mount Nyiragongo has recently been selected as one of the fifteen "Decade' volcanoes by the International Association for Volanology and Chemistry of the Earth's Interior. This was formed out of a special study during the United Nation's International Decade for Natural Disaster Reduction. During the 1970's-1990's the Nyiragongo volcano displayed the most activity. Since 1882 it has erupted at least 34 times, some periods when activity was constant for periods of years at a time. Usually this happened in the form of a churning, lava lake in the center of the volcano. This permanent pool of liquid magma was discovered by the French vulcanologist Haroun Tazieff.
Volcanism at Nyiragongo is caused by the rifting of the Earth's crust where two parts of the African Plate are breaking apart. A hot spot is probably also partly responsible for the great activity at Nyiragongo and Nyamuragira. Nyiragongo's lavas are made of melilite nephelinite, an alkali-rich type of volcanic rock whose unusual chemical composition may be a factor in the unusual fluidity of the lavas there. This type of alkaline lava has a melting temperature of two-thousand degrees Farenheit. Whereas most lava flows move rather slowly and rarely pose a danger to human life, Nyiragongo's lava flows may race downhill at up to 60 miles per hour. This is due to the composition of the lava, which has extremely low silica content, meaning that it has the composition of mafic lava. As seismic activity within the volcano increases, the crater periodically contains an active lava lake that can drain suddenly and catastrophically out of Nyiragongo, gorging the volcano's fissures with spewing fountains of fast-moving lava. This occurred during Nyiragongo's lethal eruptions in 1977 and 2002. Nyiragongo is notorious for releasing large amounts of sulfur dioxide through its many vents. At up to 50,000 tons
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