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Mt Nyiragongo Case Study
Where: Virunga National Park, of
Democratic Republic of the Congo.
Type of Volcano: Stratovolcano
Plate Boundaries: Great rift valley in
Africa splitting of the African plate
Rift Valley: the earth's tectonic forces
are presently trying to create new plates
by splitting apart old ones.
The formation is an ongoing debate.
One idea assumes that elevated heat
flow from the mantle is causing a pair of thermal "bulges" in central
Kenya and the Afar region of northcentral Ethiopia.
As these bulges form, they stretch and fracture the outer brittle crust into a
series of normal faults forming the classic structure of rift valleys.
It's though the bulges are initiated by mantle plumes under the continent
heating the overlying crust and causing it to expand and fracture.
The stretching process associated with rift formation is often preceded by
huge volcanic eruptions which flow over large areas and are usually
preserved/exposed on the flanks of the rift. These eruptions are
considered to be "flood basalts" the lava is erupted along fractures
(rather than at individual volcanoes) and runs over the land in sheets like
water during a flood. Such eruptions cover massive areas of land and
develop enormous thicknesses.
If the stretching of the crust continues, it forms a "stretched zone" of
thinned crust consisting of a mix of basaltic and continental rocks which
eventually drops below sea level, as has happened in the Red Sea and
Gulf of Aden. Further stretching leads to the formation of oceanic crust
and the birth of a new ocean basin.
Crater: (main) 2km wide and 250m deep often containing a lava lake
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Type of Lava: very fluid. made of melilite nephelinite, an alkalirich type
of volcanic rock whose unusual chemical composition may be a factor in
the unusual fluidity. flows may race downhill at up to 60 miles per hour.
Low silica content
Most Recent Eruprtion: 2001 (continuing)
2 weeks before earthquake measuring 4.8 on the richter scale
08.25 17/1/2002 massive volcano eruption
45 people died during the eruption from asphyxiation and the
collapsing of buildings.…read more
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Cost of providing food, blankets, utensils, shelter, clean water,
sanitation and healthcare estimated at $15 million
Much higher cost will occur with rebuilding Goma's infrastructure,
homes and livelihoods.
Mass unemployment from businesses destroyed by lava
The eruption of Mt. Nyiragongo on January 17, 2002 was predicted a
week earlier by a local expert who had been watching the volcanoes for
years. He informed the local authorities and a UN survey team was
dispatched to the area however, it was declared safe.…read more