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VOLCANISM

VOLCANISM. Pu'u O'o on October 3, 1997. http://volcano.und.nodak.edu/vwdocs/current_volcs/kilauea/kilauea.html. Perspective On Volcanism. Volcanoes form at: Hot Spots. Perspective On Volcanism. Volcanoes form at: Hot Spots Spreading Centers. Perspective On Volcanism. Volcanoes form at:

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VOLCANISM

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  1. VOLCANISM Pu'u O'o on October 3, 1997.http://volcano.und.nodak.edu/vwdocs/current_volcs/kilauea/kilauea.html

  2. Perspective On Volcanism • Volcanoes form at: • Hot Spots

  3. Perspective On Volcanism • Volcanoes form at: • Hot Spots • Spreading Centers

  4. Perspective On Volcanism • Volcanoes form at: • Hot Spots • Spreading Centers • Convergent Plate Boundaries • Ocean – Ocean • Ocean–Continental

  5. Lithospheric Plates

  6. Perspective On Volcanism • Volcanism threatens to destroy numerous major cities • Popocatepetl - Mexico City • Mt. Vesuvius – Naples • Mt. Merapi – Jogjakarta • Mt. Rainier – Seattle area • Mt. Hood - Portland • Huge Populations have grown in Volcanic Areas

  7. VEI (Volcanic Explosivity Index) Created by Newhall and Self (1982) and later updated by Simkin and Siebert (1994)Source: Smithsonian’s Global Volcanism Network

  8. Volcanic Hazards • Direct • Gas • Lahars (Volcanic Mudflows) • Lava flows • Pyroclastic Flows • Tsunami • Indirect • Famine

  9. Benefits of Volcanoes • Produce great amounts of new land • Frequently produce very fertile soils • Provide Geothermal Power • Recreation

  10. Volcanoes of the World http://volcano.und.nodak.edu/vwdocs/volc_images/volc_images.html

  11. Volcanic Hazards in Developing Nations - Africa

  12. Africa – Geologic Overview • 200 m.y.a. - Breakup of Pangaea • ~55 m.y.a. – Afro-Arabian rifting began • Most African volcanoes are the result of hot spots, rifting, or a combination of the two.

  13. Cameroon – Mt. Cameroon • Population: 16,063,678 • Government • Generally stable, political power is an ethnic oligarchy. • Natural hazards • volcanic activity from Lake Nyos and Lake Monoun volcanoes • Current issues include: • water-borne diseases prevalent; deforestation; overgrazing; desertification; poaching; overfishing

  14. Cameroon – Mt. Cameroon • Type of volcano: stratovolcano • Known to locals as Mount Faka and “Chariot of the Gods” • Eruptions occur on the flanks of the volcano • Cinder cones and lava flows

  15. Cameroon – Mt. Cameroon • 1999 – 2000 eruption • Primarily basaltic lava flows • Many villages threatened, evacuations ordered • Many roads disrupted Photo by J. P. Lockwood Average thickness of flow is 10-12 m, 33-39 ft.

  16. Cameroon – Lake Nyos • Type of volcanism: Maar • A volcanic crater that is produced by an explosion in an area of low relief, is generally more or less circular, and often contains a lake, pond, or marsh. (http://volcano.und.nodak.edu/vwdocs/glossary.html) Landsat image of Lake Nyos processed by Sarah Sherman, April 2000.

  17. Cameroon – Lake Nyos • Maars in Oku volcanic field formed during an explosive eruption of carbon dioxide gas • Lake Nyos formed about 400 years ago

  18. Cameroon – Lake Nyos • August of 1986 Lake Nyos • 1 km of CO2 released • ~1700 people killed up to 26 km away from the lake • August of 1984 • smaller gas burst from Lake Monoun • 37 people killed Photo by Jack Lockwood, U.S. Geological Survey

  19. Cameroon – Lake Nyos • Only three lakes in the world are known to contain high concentrations of dissolved gas in their bottom waters: • Lakes Nyos and Monoun in Cameroon • and Lake Kivu in East Africa. • Only Lakes Nyos and Monoun are known to have recently released gas resulting in the loss of human life. Using Science to Solve Problems: The Killer Lakes of Cameroon By Dr. George Kling

  20. African Rift Zone • Type of volcanism: Rifting • Two branches: • Eastern or Great Rift zone • Jordan River, the Dead Sea, and the Gulf of Aqaba. • The Red Sea • Ethiopian Denakil Plain to Lakes Rudolf (Turkana), Naivasha, and Magadi in Kenya. • Shire River valley and Mozambique Plain to the coast of the Indian Ocean near Beira, Mozambique

  21. African Rift Zone • Type of volcanism: Rifting • Two branches: • Western zone • Extends from Lake Nyasa north through Lakes Rukwa, Tanganyika, Kivu, Edward, and Albert.

  22. Goma & Nyiragongo, Congo Lake Nyos, Cameroon Western Rift Zone

  23. Nyiragongo, Democratic Republic of Congo (Zaire) • Population: 58,317,930 • Government • Dictatorship; ethnic strife and civil war, touched off by a massive inflow of refugees from the fighting in Rwanda and Burundi

  24. Nyiragongo, Democratic Republic of Congo (Zaire) • Natural hazards • periodic droughts in south; Congo River floods (seasonal); active volcanoes in the Great Rift Valley • Current issues include: • poaching threatens wildlife populations; water pollution; deforestation; refugees responsible for significant deforestation, soil erosion, and wildlife poaching;

  25. Nyiragongo, Democratic Republic of Congo (Zaire) • Type of volcanism: Stratovolcano (in EARZ) • Formed ~20,000 years ago • One of the “Decade” Volcanoes

  26. Nyiragongo, Democratic Republic of Congo (Zaire) • Recent Eruptions • 1977 • lava lake in crater drained in <1 hour • flank eruptions moved at 40 mph • 70 deaths from one eruption, 2000 deaths total for the year • Eruption formed a fracture system that led partway down to the city of Goma

  27. Nyiragongo, Democratic Republic of Congo (Zaire) • Recent Eruptions • 2002 • Lavas unusually low in SiO2 • Flowed rapidly down the slope, through the city of Goma to Lake Kivu • 45 people killed • City of Goma largely destroyed, refugee crisis

  28. Nyiragongo, Democratic Republic of Congo (Zaire) January 17, 2002, less than 1 hour after the eruption began. Hot spots

  29. Nyiragongo, Democratic Republic of Congo (Zaire) • Nyiragongo Volcano Erupts • Ash and steam were pouring from the Nyiragongo Volcano on July 12, 2004, when the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard NASA’s Terra satellite captured this image. • http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16606

  30. Nyiragongo, Democratic Republic of Congo (Zaire) Computer Mapping of Nyiragongo Volcano This computer-generated visualization combines a Landsat satellite image and an elevation model from the Shuttle Radar Topography Mission (SRTM) to provide a view of Nyiragongo Volcano (right of center) and the city of Goma (pink area along shoreline in foreground), located in the Democratic Republic of Congo http://earthobservatory.nasa.gov/Study/monvoc/monvoc2.html

  31. Lava lake at Nyiragongo. Photograph of the lava lake by Jack Lockwood, U.S. Geological Survey, August 24, 1994.

  32. East African Rift Zone

  33. Questions to ponder . . . • Many African nations are in a period of civil and political unrest • Ethnic “cleansing” • Civil war • Poverty • Famine • Drought • How might a volcanic eruption affect the population?

  34. Volcanic Hazards in Developing Nations – the Middle East

  35. Harrat Hutaymah, Saudi Arabia • Population: 25,795,938 • Government • Generally stable, monarchy. • Natural hazards • frequent sand and dust storms • Current issues include: • desertification; depletion of underground water resources; lack of perennial rivers or permanent water bodies; coastal pollution from oil spills

  36. Harrat Hutaymah, Saudi Arabia • Volcanism is the result of rifting • "Harrat" is Arabic word which means "stony area volcanic country or lava field." • Volcanism assymetric

  37. Harrat Al Birk, Saudi Arabia • Dark-colored volcanic cones sprout from an ancient lava field known as Harrat Al Birk along Saudi Arabia's Red Sea coastline. • Many such lava fields dot the Arabian Peninsula and range in age from 2 million to 30 million years old. • http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=16517

  38. Harrat Hutaymah, Saudi Arabia • Tabah • Small town in a tuff ring

  39. Questions to ponder . . . • While there is not a large population base in the volcanic province of Saudi Arabia, there are several important cities within it. • What would happen if volcanic activity commenced near the holy city of Mecca?

  40. Volcanic Hazards in Developing Nations – SE Asia

  41. Indonesia – Geologic Overview • Comprised of more than 13,000 islands • Volcanic island arcs • Sunda Arc - subduction of Australian-Indian Plate beneath the Asian Plate = Java Trench • Banda Arc - subduction of Pacific Plate beneath the Philippine Sea Plate = Marianas Trench

  42. Indonesia – Geologic Overview • Largest number of active volcanoes (76) • 1,171 dated eruptions (second only to Japan)

  43. Krakatoa (Krakatau), Indonesia • Type of volcano: resurgent caldera • Inactive for 200 years before 1883 • Eruption began in May and climaxed on August 26 & 27 • VEI = 6 • Lava, ash, and gas erupted • Ash covered neighboring islands • Pumice choked the Sunda Strait

  44. Krakatoa (Krakatau), Indonesia • Eruption began in May and climaxed on August 26 & 27 • Suddenly 10 sq miles collapsed • A strong earthquake occurred • Sound could be heard 3000 miles away • Tsunami over 100 feet high killed 36,000 people in Java and Sumatra

  45. Toba, Sumatra • Type of volcano: stratovolcano • Last erupted 74,000 years ago • The resultant caldera formed Lake Toba, 100 km long, 60 km wide • 3,000 km3 of ejected material + large quantities of SO2

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