Volcanoes in Africa
Adapted from: Simpkin and Siebert, 1994, Volcanoes of the World:Africa is the only region other than the Mediterranean with an historically dated B.C. eruption (at Mount Cameroon, observed by a passing Carthaginian navigator in the 5th century B.C.). By the 15th centuray A.D., however, when Portuguese exploration of Africa had begun and Vasco de Gama sailed to India via the Cape of Good Hope, only 2 more eruptions had been recorded, both from Ethiopia. In the next 3 and two-thirds centuries, another 20 some eruptions were recorded, but the main historical record of the continent began with the opening of the Suez Canal at the end of 1869, and the heyday of African exploration that followed.
Most African volcanoes result from hotspots, the rifting in East Africa, or a combination of the two. The East African rift, one of the world's most dramatic extensional structures, has produced the continent's highest and lowest volcanoes, ranging from the massive Kilimanjaro to vents in Ethiopia's Danakil Depression that lie below sea level.
Two neighboring volcanoes in Zaire's (today's Democratic Republic of the Congo) Virunga National Park, Nyamuragira and Nyiragongo, are responsible for nearly two-fifths of Africa's historical eruptions.
Active volcanoes in Africa
Schematic map of Africa's most active volcanoes
The East African Rift Valley
Map of East Africa showing some of the historically active volcanoes (red triangles) and the Afar Triangle (shaded, center) -- a so-called triple junction (or triple point), where three plates are pulling away from one another: the Arabian Plate, and the two parts of the African Plate (the Nubian and the Somalian) splitting along the East African Rift Zone.
From: Kious and Tilling, 1996, This Dynamic Earth: The Story of Plate Tectonics: USGS Online version 1.08
In East Africa, spreading processes have already torn Saudi Arabia away from the rest of the African continent, forming the Red Sea. The actively splitting African Plate and the Arabian Plate meet in what geologists call a triple junction, where the Red Sea meets the Gulf of Aden. A new spreading centre may be developing under Africa along the East African Rift Zone. When the continental crust stretches beyond its limits, tension cracks begin to appear on the Earth's surface. Magma rises and squeezes through the widening cracks, sometimes to erupt and form volcanoes. The rising magma, whether or not it erupts, puts more pressure on the crust to produce additional fractures and, ultimately, the rift zone.
East Africa may be the site of the Earth's next major ocean. Plate interactions in the region provide scientists an opportunity to study first hand how the Atlantic may have begun to form about 200 million years ago. Geologists believe that, if spreading continues, the three plates that meet at the edge of the present-day African continent will separate completely; allowing the Indian Ocean to flood the area and making the easternmost corner of Africa (the Horn of Africa) a large island.
The enemy is still there’: Sergio Galilea, Intendente of Los Lagos Region, Chile, talking about Chaitén volcano on the first anniversary of its eruption. Interview with Radio Cooperativa, 2 May 2009.
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The Daily Volcano Quote: volcanoes are part of the universalorder 7 May 2009
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Volcanoes form no exception to the principles of universal order. They may appear to be physical flaws, and to assume the character of accidents. The devastation which they have produced lead men to regard them very naturally as evils. But two things are certain. They arrive from the operation of natural causes which, however secret, hidden, and difficult of discovery, science may approach with a firm conviction that they are within its domain. And they subserve important and beneficent ends, some of which are already well understood.
John Kennedy, Volcanoes: Their History, Phenomena, and Causes (London: Religious Tract Society, 1852), pp. 7-8.
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The Daily Volcano Quote: the causes of eruptions(1693) 6 May 2009
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The Reason of these Fires is the Abundance of SULPHUR and BRIMSTONE, contain’d in the bosome of the Hill; which is blown by the Wind, driving it in at the Chaps of the Earth, as by a pair of Bellows … Now, whether these Eruptions are caused by actual Subterraneous Fires, lighting upon Combustible Matter; Or by Fire struck out of falling and breaking Stones, whose Sparks meet with Nitro-Sulphureous or other inflammable Substance heap’d together in the Bowels of the Earth, and by the Expansive violence of the Fire forc’d to take more room, and so bursting out with the impetuousity we see; may not be unworthy of a Philosopher’s Speculation.
Sir Thomas Blount, A Natural History: Containing Many not Common Observations: Extracted out of the best Modern Writers (London, 1693), pp. 398-9. More on Blount’s Natural History here.
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The Daily Volcano Quote: an extinct volcano not a safeneighbour 5 May 2009
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We likewise forget, in these cool districts of the earth, that we are not quite beyond the hazard of subterranean fire. There are numberless extinct volcanoes in both Britain and France; there are some on the banks of the Rhine; indeed, they are thick-sown everywhere. Now an extinct volcano is not quite so safe a neighbour as many may suppose. Vesuvius was an extinct volcano from time immemorial till the year 63, when it suddenly broke out again, and soon after destroyed Pompeii and Herculaneum; since which time it has never again subsided into entire inactivity. Suppose Arthur’s Seat, which is ‘within a mile of Edinburgh town’ were to recommence business in like manner, we should like to know at how many years’ purchase house property in that beautiful New Town would be selling next day. Yet what is there about an old volcano there more than an old volcano in Italy, to give assurance that its means of annoyance and destruction are extinguished?
‘A possible event — dangers of our planet’, The National Magazine, November 1854, p. 435.
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The Daily Volcano Quote: volcanic risks remote, notcertain 4 May 2009
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Persons unaccustomed to volcanic regions frequently express astonishment at what they call the foolhardiness of those who inhabit such localities. But the risk is less than is supposed. Such districts enjoy a remarkable immunity from epidemics, and even from the ordinary diseases which shorten human life, so that it is doubtful whether, on the average, the chances of a protracted existence are not greater there than in most other places. Besides, the peril of living near a volcano is remote, not certain; and each generation, as well as individual, indulge the hope of exemption from the threatened danger. To put an every-day illustration, there is as much risk in railroad-travelling as in cultivating fields on the flank of a volcano; yet there are but few who decline a journey from fear of the cars.
‘Eruptions of Vesuvius’, The Friend, vol. XXVIII (1855), p. 410.
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The Daily Volcano Quote: Craig Arnold, volcanopilgrim 1 May 2009
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The Volcano Pilgrim has dedicated the last three years to the belief that one need not shrink from the sublime. Nay, rather, one may seek it out, with a pack on your back and a stick in your hand, liberal applications of sunblock and when necessary a gas mask over your face.
He recognizes that chasing this particular dragon may not strike some people as entirely healthy or balanced behavior, but the nature of that imbalance is one of the things he hopes in the course of the journey to understand.
And he has found that, when you’re clambering up the side of a smoking mountain, driven by apocalyptic fantasies of fiery death, many things may catch your attention along the way – birds, beasts, flowers, people. Though he doubts Basho would have shared his love for lava, he suspects the master would recognize the restlessness that sends one out searching for it.
Craig Arnold, ‘The Volcano Pilgrim – 火山巡礼者’, at his website Volcano Pilgrim: five months in Japan as a wandering poet.
Craig Arnold is a professor at the University of Wyoming and an award-winning poet with a deep interest in and passion for volcanoes. He set out on a hike around the volcanic island of Kuchinoerabu-jima on Monday and failed to return. A search is under way.
News
UW professor missing in Japan – University of Wyoming, 30 April 2009
Craig Arnold search – University of Wyoming, 30 April 2009
U.S. professor disappears during Japan volcano hike – CNN, 30 April 2009
University of Wyoming professor missing in Japan – NPR, 30 April 2009
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The Daily Volcano Quote: volcanically induced climatechange 30 April 2009
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Where archaeologists and palaeoenvironmentalists have proposed the eruption of a distant volcano as the cause of cultural change or environmental stress, they have frequently invoked volcanically generated climate change as the mechanism. However, volcanically induced climate change has been shown to be on a relatively minor scale and no eruption of the past 3000 years has reduced hemispheric temperature by more than 1°C, which is within normal fluctuation and hardly of itself likely to bring about long-lasting cultural or environmental change. In historical times, where poor weather has been coincident with volcanic eruptions and demonstrated social and environmental stress, pre-existing social, cultural, economic, environmental and climatic trends have been in evidence and it is the combination of these that is significant, not the remote influence of a distant volcanic eruption. Where these cannot be identified in the archaeological record, volcanogenic climate change is a theoretical tool which must be used with caution.
John Grattan, Mark Brayshay & Ruud T. E. Schüttenhelm, ‘”The end is nigh”? Social and environmental responses to volcanic gas pollution’, in Robin Torrence & John Grattan (eds.), Natural Disasters and Cultural Change (London: Routledge, 2002), p. 88.
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The Daily Volcano Quote: Vancouver gets Mount Hood’s heightwrong 29 April 2009
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When the English explorer, Vancouver, who gave Mt. Hood its name, first saw the mountain, he estimated its height to be at least 25,000 feet, and thought it was perhaps the highest summit in the world. Barometric and other measurements, however, made by the United States Coast Survey and by the Fortieth Parallel Survey, have shown that Vancouver’s estimate was more than twice the actual height. In spite of the corrections that prosaic measurements have imposed upon the fancy of distant observers, Mt. Hood, if not the most lofty, is, yet, in the eyes of its admirers, one of the most beautiful of mountains.
Israel C. Russell, Volcanoes of North America (London: Macmillan, 1897), pp. 237-8. The summit of Mount Hood is 3426 metres (11240 feet) above sea level.
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The Daily Volcano Quote: prospects for geothermal energy,1928 28 April 2009
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The huge reservoir of volcanic energy represented by the heat of rocks and gases could undoubtedly be tapped in many places and used for power production … I believe that in time to come the greatest of all sources of power will be found in the subterranean storehouses of volcanic regions, where the internal heat of the earth can be reached at a relatively shallow level. The limited supplies of coal and oil in the earth will be exhausted in the comparatively near future. The waterpower available in rivers is already to a large extent taken up. Water-power from the tides will probably prove costly to utilize, and the same is likely to be true of any method now in sight of using direct solar energy … On the other hand, no insurmountable obstacles seem to exist to tapping the earth’s internal heat on a vast scale, and volcanology is paving the way to this accomplishment.
Dr Immanuel Friedlander, quoted in Science News-Letter, 14 January 1928, p. 23.
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The Daily Volcano Quote: Empedocles onEtna 27 April 2009
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… And thou, fiery world,
That sapp’st the vitals of this terrible mount
Upon whose charr’d and quaking crust I stand,
Thou, too, brimmest with life! — the sea of cloud
That heaves its white and billowy vapours up
To moat this isle of ashes from the world,
Lives! — and that other fainter sea, far down,
O’er whose lit floor a road of moonbeams leads
To Etna’s Liparëan sister-fires
And the long dusky line of Italy —
That mild and luminous floor of waters lives,
With held-in joy swelling its heart!