VOLCANISM Puu Oo on October 3 1997 http
VOLCANISM Pu'u O'o on October 3, 1997. http: //volcano. und. nodak. edu/vwdocs/current_volcs/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
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. html
Volcanic Hazards in Developing Nations - Africa
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.
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 CO 2 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 Si. O 2 • 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/New. Images/images. php 3? 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 2. 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 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/New. Images/images. php 3? 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 km 3 of ejected material + large quantities of SO 2
Toba, Sumatra – Ash and SO 2 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 mi 2 – 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 1500 s • 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, 1980 s – 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?
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