Transcript Volcanism-World

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 ~