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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: – Hot Spots – Spreading Centers – Convergent Plate Boundaries • Ocean – Ocean • Ocean–Continental Lithospheric Plates 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 Deadliest Volcanic Eruptions Since 1500 A.D. Eruption Year Casualties Major Cause 1,3 Mudflows 3 Nevado del Ruiz, Colombia 1985 Mont Pelée, Martinique 1902 30,0001 (29,025)2 Pyroclastic flows 2 Krakatau, Indonesia 1883 36,0001 (36,417)2 Tsunami2 Tambora, Indonesia 1815 92,0001,2 Starvation2 25,000 Volcano collapse, Unzen, Japan 1 2 1792 15,000 (14,030) Tsunami2 Lakagigar (Laki), Iceland 1783 9,0001 (9,350)2 Starvation2 Kelut, Indonesia 1586 100,001 Mount Pinatubo, Philippines 1991 3503 Roof Collapse3 Mount St. Helens, Washington 1980 573 Asphyxiation from ash Kilauea, Hawaii 1924 11 Falling rock 1 Lassen Peak, California 1915 4 79 A.D. 33,602 Other Notable Eruptions Mount Vesuvius, Italy Sources 1 Tilling, Topinka, and Swanson, 1990, Eruptions of Mount St. Helens: Past, Present, and Future: U.S. Geological Survey General Interest Publication, 56p. 2 Blong, R.J., 1984, Volcanic Hazards: A Sourcebook on the Effects of Eruptions: Orlando, Florida, Academic Press, 424p. 3 Wright and Pierson, 1992, Living With Volcanoes: The U.S. Geological Survey's Volcano Hazards Program: U. S. Geological Survey Circular 1073, 57p. 4 Spall, H. (ed.), 1980, Earthquake Information Bulletin: July-August, 1980, v.12, no.4, 167p. Pyroclastic Flow2 VEI (Volcanic Explosivity Index) Created by Newhall and Self (1982) and later updated by Simkin and Siebert (1994) Source: Smithsonian’s Global Volcanism Network Volcanic Hazards • Direct – – – – – Gas Lahars (Volcanic Mudflows) Lava flows Pyroclastic Flows Tsunami • Indirect – Famine Benefits of Volcanoes • • • • Produce great amounts of new land Frequently produce very fertile soils Provide Geothermal Power Recreation Volcanoes of the World http://volcano.und.nodak.edu/vwdocs/volc_images/volc_images.html Volcanic Hazards in Developing Nations - Africa Africa – Geologic Overview • 200 m.y.a. Breakup of Pangaea • ~55 m.y.a. – AfroArabian rifting began • Most African volcanoes are the result of hot spots, rifting, or a combination of the two. 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 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 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, 3339 ft. 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/vwdo cs/glossary.html) Landsat image of Lake Nyos processed by Sarah Sherman, April 2000. Cameroon – Lake Nyos • Maars in Oku volcanic field formed during an explosive eruption of carbon dioxide gas • Lake Nyos formed about 400 years ago 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 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 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 African Rift Zone • Type of volcanism: Rifting • Two branches: – Western zone • Extends from Lake Nyasa north through Lakes Rukwa, Tanganyika, Kivu, Edward, and Albert. Lake Nyos, Cameroon Goma & Nyiragongo, Congo Western Rift Zone 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 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; Nyiragongo, Democratic Republic of Congo (Zaire) • Type of volcanism: Stratovolcano (in EARZ) • Formed ~20,000 years ago • One of the “Decade” Volcanoes 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 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 Nyiragongo, Democratic Republic of Congo (Zaire) January 17, 2002, less than 1 hour after the eruption began. Hot spots 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/Newsroo m/NewImages/images.php3?img_id=166 06 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 Lava lake at Nyiragongo. Photograph of the lava lake by Jack Lockwood, U.S. Geological Survey, August 24, 1994. East African Rift Zone 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? Volcanic Hazards in Developing Nations – the Middle East 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 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 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/Newsr oom/NewImages/images.php3?img_id= 16517 Harrat Hutaymah, Saudi Arabia • Tabah – Small town in a tuff ring 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? Volcanic Hazards in Developing Nations – SE Asia 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 Indonesia – Geologic Overview • Largest number of active volcanoes (76) • 1,171 dated eruptions (second only to Japan) 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 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 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 Toba, Sumatra – Ash and SO2 ejected into the stratosphere reflects solar radiation back into space – Est. global cooling of 5ºC – 15 ºC in temperate & high latitudes – Genetic research on mitochondrial DNA Tambora, Indonesia • Type of volcano: Stratovolcano • 1815 eruption – Largest eruption in historic time (VEI = 7) – Caldera-forming eruption – Numerous pyroclastic flows • 10,000 deaths – Pyroclastic fallout destroyed crops in Indonesia • 82,000 deaths – Affected global climate – 1816 “year without a summer Kelut, Indonesia • Type of volcano: Stratovolcano • Eruptions of 1586 & 1919 – VEI = 5? – Large crater lake at summit – Pyroclastic eruptions + water from lake = lahar • Eruptions make for fertile soil, so heavily populated • Last eruption: 1990 – VEI=4 – produced a large cloud and heavy tephra fall – 32 people killed Questions to ponder . . . • Current issues include (from CIA World Fact book): – Poverty – Terrorism – Political unrest – Human rights violations – Separatist pressures in Aceh and Papua. • Indonesia’s volcanoes are very destructive – how might a large volcanic eruption affect the region? Volcanic Hazards in Developing Nations – Latin America Latin America – Geologic Overview • Mexico & Central America – Volcanism due to subduction of the Pacific and Cocos Plates beneath the North American & Caribbean Plates • South America – Volcanism due to subduction of the Nazca Plate beneath the South American Plate Paricutin, Michoacan, Mexico • Type of volcano: Cinder Cone • 1943 eruption – – – – cinder cone developed in a farmer’s field Erupted for 9 years, built a cone Pyroclastic debris & lava flows buried 100 mi2 Destroyed the towns of Paricutin and San Juan de Paragaricutiro Paricutin, March 1944. From Foshag and Gonzalez-Reyna (1956) Slide show on the evolution of Paricutin prepared by Scott Rowland. The church at Paricutin. Photograph by K. Segerstrom, U.S. Geological Survey, 1948 Popocatépetl, Mexico • Type of volcano: stratovolcano • Located ~70 km southeast of Mexico City • Erupted 36 times since the arrival of the Spanish conquistadors in the 1500s • Most recent: 1994 – 1997 Popocatépetl, Mexico • 1994 eruption – Began just before Christmas – Heavy ashfall = evacuation of 19 villages (31,000 people) – Increased activity = 75,000 people evacuated • Today – Still erupting some ash and gas Colima, Mexico • Type of volcano: Stratovolcano • One of the “Decade” Volcanoes • Comprised of two volcanoes: – Nevado de Colima – Volcan de Colima (historically active) • 125 km (75 miles) south of Guadalajara Colima, Mexico • January 20, 1913 eruption – Only 4 days long – Produced ash flows and a summit crater • 1961, 1975, 1980s – Minor lava flows • 1987 & 1994 – Explosive eruptions • 1998 – Present – Explosive eruptions, ash, formation of lava dome & lava avalanches Colima, Mexico • Concern is that the volcano has a history of pyroclastic flows and large avalanches JPL image Nevado del Ruiz, Columbia • Type of volcano: Stratovolcano • Eruptions – 2 eruptions on Nov 13, 1985 melted the summit glaciers – Mudflows travelled in all directions from the summit – Mud traveling 30 mph & 50 feet deep buries Amero 30 miles away – 25,000 killed Questions to ponder • Many Latin American countries are experiencing large population growths • Volcanoes typically have very fertile soils. • Should new populations be allowed to live on/near volcanoes? ~ End ~