SUPERVOLCANO
Banjal, S
Suarez,L
Buenavista,A
2011
TYPES OF MAGMA
Basaltic
Andesitic
Rhyolitic
What gives the explosive character of the
magma?
Ans. Gas content
H20 (water vapor) and CO2
Minor: S, Cl, F gases
Temperature of Magma
B- 1000 to 1200 ‘C
A- 800 to 1000 ‘C
R- 650 to 800
‘C
What is viscosity?
resistance to flow
Depends?
Composition and temperature
Summary Table
Magma
Type
Solidified
Rock
Chemical Composition
Temperature
Viscosity
Gas Content
Basaltic
Basalt
45-55 SiO2 %,
high in Fe, Mg, Ca,
low in K, Na
1000 - 1200 oC
10 - 103 PaS
Low
Andesitic
Andesite
55-65 SiO2 %,
800 - 1000 oC
intermediate in Fe, Mg, Ca, Na, K
103 - 105 PaS
Intermediate
Rhyolite
65-75 SiO2 %,
low in Fe, Mg, Ca,
high in K, Na.
105 - 109 PaS
High
Rhyolitic
650 - 800 oC
How magmas (melts) are formed?
-temp must be high enough to melt to rocks
-under normal geothermal gradient, it is not enough to
melt rocks
-magma forms only on special circumstances
Pure Minerals
Minerals and/or
surroundings contains
“NO”
H2O and CO2
-melting occurs at single
temp.-pressure
-increasing in increasing
depth
DRY MELTING
Pure Minerals
Minerals and/or
surroundings
contains
H2O and CO2
-melting occurs at
single temp.-pressure
-decreasing to
increasing pressure
trend
WET MELTING
ROCKs-partial melting
-similar to dry melting
of minerals, except
there is a range of
temp. over existing
partial melt.
- 0%- 100% melt
DRY MELTING
ROCKs-partial melting
-similar to wet melting
of minerals, except
there is a range of
temp. over existing
partial melt.
- 0%- 100% melt
- -decreasing to
increasing pressure
trend
DRY MELTING
Origin of Basaltic Magma
-make up most of oceanic crust
and mantle
- Mantle is made of garnet
peridotite (olv,garnet,pyx)
- Lab test indicate normal
geothermal gradient, lower to
begin melting
- Convection rises the local
geothem thus initiate partial
melting.
- Liquid can be separated to
crystal due to differential
density.
Decompression Melting
Origin of Rhyolitic Magma
-found in continental areas
-explosive due to high gas
content
-qtz,feld,hornde,biotote,musco.
Minerals containing H2o
-heat source is basaltic magma
-rises to continental crust
-basaltic magma is
denser,sometimes stops , cause
partial melting to the crust
producing rhyolitic magma
Origin of Andesitic Magma
-erupts in areas above subduction zones
- Earlier theory sugg. Wet partial melting of subducted oceanic
lith.,
- New theories sugg. Wet partial melting of mantle
- Water:
- contained in spore spaces on upper oceanic lith.
- Clay minerals settle to the seafloor
LOWERS melting temp - MELTING
• A volcano is an opening, or rupture, in a planet's
surface or crust,
• allowing hot magma, volcanic ash and gases to
escape from below the surface.
SUPERVOLCANO
-volcano capable of producing a volcanic eruption with
ejecta greater than 1,000 cubic km
-occurs when magma rises to crust from hotspots and there
is build up of pressure (large growing magma pool) until
it cannot hold on the pressure
Resulting to….
PHREATIC
PLINIAN
STROMBOLIAN
VULCANIAN
PELEAN
• forms also in continental hotspots (eg. yellow
stone) and convergent plate boundaries (eg.
Toba)
Supervolcanoes Around The World
Supervolcano
Long Valley
Valley Grande
Lake Taupo
Aira
Lake Toba
Siberian Traps
Yellowstone
VEI
Ejecta volume
Classification
Description
Plume
Frequency
Example
Occurrences in
last 10,000
years*
0
< 10,000 m³
Hawaiian
non-explosive
< 100 m
constant
Kilauea
many
1
> 10,000 m³
Hawaiian/Stro
mbolian
gentle
100–1000 m
daily
Stromboli
many
2
> 1,000,000 m³
Strombolian/Vu
explosive
lcanian
1–5 km
weekly
Galeras (1993)
3477*
3
> 10,000,000
m³
Vulcanian/Pelé
severe
an
3–15 km
yearly
Cordón
Caulle (1921)
868
4
> 0.1 km³
Peléan/Plinian
10–25 km
≥ 10 yrs
Eyjafjallajökull (
421
2010)
≥ 50 yrs
Mount St.
Helens(1980)
Mount Mayon
(1814)
5
cataclysmic
> 1 km³
Plinian
paroxysmal
> 25 km
166
6
> 10 km³
Plinian/UltraPlinian
colossal
> 25 km
≥ 100 yrs
Mount
Pinatubo (1991, 51
Jun 15
7
> 100 km³
Plinian/UltraPlinian
super-colossal
> 25 km
≥ 1000 yrs
Tambora (1815)
5 (+2
suspected)
8
> 1,000 km³
Ultra-Plinian
mega-colossal
> 25 km
≥ 10,000 yrs
Taupo (26,500
BP)
0
TERMINOLOGY
Term “supervolcano” was orig. used in BBC popular science tv
program HORIZONS in 2000 refer as TYPE of ERUPTIONs.
Introduced Large scale vol. eruption to public
-geologist and volcanologist-don’t refer it in scientific works.
-eruption that rate VEI 8 are also termed “supervolcano”
2 type of vol. eruption identified as SV:
-Large Igneous Provinces
-Massive Eruptions
Large Igneous Provinces
Only a few of the largest Large Igneous Provinces are
indicated (by the dark purple areas) on this
geological map, which depicts crustal geologic
provinces as seen in seismic refraction data.
....are extremely large accumulations of igneous rocks—either
intrusive, extrusive, or both—which are found in the earth's
crust.
-Coffin and Eldholm (1992)
>term it LIP refer greater that 100,000 km2 of mafic ign:
erupted, emplaced at depth in extremely short geol. Time (few
mya or less)
Today: includes felsic to intermediate ign.
Attributed:
-mantle plumes
-plate tectonics
Siberian Traps
-largest flood basalt event
-area covered is about 2 million
km²
-estimates of the original
coverage are as high as
7 million km²
-vol. 1 to 4 million km³.
-around 251mya
-coincide largest mass extinction
history (end Permian)
Deccan Traps (India)
-multiple layers of solidified flood basalt
-more than 2,000 m
-area of 500,000 km2 and volume of 512,000
km3
-65 mya
-coincide with 2nd largest extinction events
(end of cretaceous)
Relationship of LIP to extinction events
-eruption of Basaltic LIP release large vol. of sulfate gas,
forms sulfuric acid (poisonous, severe burns all body
tissues, harmful to inhale ); this absorbs heat and causes
substantial cooling
- Oceanic LIP's can reduce oxygen in seawater by either direct
oxidation reactions with metals in hydrothermal fluids or by
causing algal blooms that consume large amounts of oxygen
LIPs and Ore deposits
•
•
•
•
Ni-CU PGE's (Platinum Group Elements)
Porphyries (Co, Mo, Au, Ag, and Sb)
Iron oxide copper gold (IOCG)
Kimberlites (caused by subduction)
Massive Explosive Eruptions
-Eruptions with VEI 7 and 8
1,000 km3 Dense Rock Equivalent (DRE) of ejecta; VEI-7
events eject at least 100 km3 (DRE).
DRE-Dense Rock Equivalent
-volcanic calculation to estimate vol. eruption volume
Geologic gather data by:
-mapping distribution and thickness of deposited eruption
-and erosion correction (void spaces measurements to get estimate
original volume of rock)
Widely accepted measurements:
1. Volume of tephra (vol.ash and pumice) ejected
2. Vol. of lava extruded during effusive phase of volcanic eruptions
Volcanic Explosivity Index (VEI)
-Chris Newhall (USGS) & Stephen Self (Univ. of Hawaii) (1982)
provide a relative measure of the explosiveness of volcanic eruptions.
Explosive Value
1. Volume of Products
2. Eruption cloud height
3. Qualitative observations (using terms ranging from
"gentle" to "mega-colossal")
4. Duration in hours
VEI and ejecta volume
correlation
Every increase in VEI will
increase 10X the power
eruption.
VEI
Volcano (eruption)
Year
0
Hoodoo Mountain
7050 BC?
0
Mauna Loa
1984
0
Lake Nyos
1986
0
Piton de la Fournaise
2004
1
Wells Gray-Clearwater
volcanic field
1500?
1
Kilauea
1983–present
1
Nyiragongo
2002
2
Mount Hood
1865–1866
2
Kilauea
1924
2
Tristan da Cunha
1961
2
Mount Usu
2000–2001
2
Whakaari/White Island
2001
3
Mount Garibaldi
9,300 BP
3
Nazko Cone
7,200 BP
3
Mount Edziza
950 AD ± 1000
years
3
Mount Vesuvius
1913–1944
3
Surtsey
1963–1967
3
Eldfell
1973
3
Nevado del Ruiz
1985
3
Mount Etna
2002–2003
4
Mount Pelée
1902
4
Parícutin
1943–1952
4
Hekla
1947
4
Galunggung
1982
4
Mount Spurr
1992
4
Mount Okmok
2008
4
Eyjafjallajökull
2010
4
Mount Merapi
2010
5
Hekla (Hekla 3
eruption)
1021 + 130/-100 BC
5
Mount Meager
≈400 BC (2350 BP)
5
Mount
Vesuvius (Pompeian 79
eruption)
5
Mount
Edgecumbe/Pūtaua
ki
c. 300
5
Mount Tarumae
1739
5
Mount Mayon
1814
5
Mount Tarawera
1886
5
Katla
1918
5
Mount Agung
1963
5
Mount St. Helens
1980
5
El Chichón
1982
5
Mount Hudson
1991
5
Chaiten
2008
6
6
6
6
6
6
Morne Diablotins
Laacher See
Nevado de Toluca
Mount Okmok
Mount Etna
Mount Veniaminof
30,000 BP
12,900 BP?
10,500 BP
8300 BP
8000 BP?
1750 BC
6
Mount Vesuvius (Avellino eruption)
1660 BC ± 43 years
6
6
6
6
6
Grímsvötn
Mount Aniakchak
Mount Okmok
Ambrym
Ilopango
8230 BC ± 50 years
≈1645 BC
c. 400 BC
c. AD 100
450 ± 30 years
6
Mount Churchill (White River Ash)
≈750 (1200 BP)
6
Katla (Eldgjá)
934
6
Baekdu Mountain (Tianchi eruption)
969 ± 20 years
6
6
6
6
6
6
6
6
Kuwae
Bárðarbunga
Huaynaputina
Laki
Krakatoa
Santa María
Novarupta
Mount Pinatubo
1452 or 1453
1477
1600
1783
1883
1902
1912
1991
7
Sesia Valley caldera
280 Ma[2]
7
Bennett Lake Volcanic Complex
50 Ma
7
Valles (Lower Bandelier eruption)
1.47 Ma
7
Yellowstone (Mesa Falls eruption)
1.3 Ma
7
Valles (Upper Bandelier eruption)
1.15 Ma
7
Long Valley Caldera (Bishop eruption)
759,000 BP
7
Maninjau
280,000 BP
7
Atitlán (Los Chocoyos eruption)
84,000 BP
7
Kurile (Golygin eruption)
41,500 BP
7
7
Campi Flegrei
Aira Caldera
37,000 BP
22,000 BP
7
Kurile (Ilinsky eruption)
≈6400 BC
7
Crater Lake (Mount Mazama eruption)
≈5700 BC
7
Kikai (Akahoya eruption)
≈5300 BC
7
Thera (Minoan eruption)
1620s BC
7
Taupo (Hatepe eruption)
186
7
Mount Tambora (1815 eruption)
1815
Lake Toba
-Sumatra, Indonesia
-VEI 8
-69,000-77,000 years ago eruption
-largest explosive eruption anywhere
on Earth in the last 25 million years
-DRE is ~2,800 km3
-catastrophe theory holds that
this supervolcanic event plunged the
planet into a 6-to-10-yearvolcanic winter
-some anthropologists and
archeologists believed it resulted in the
world's human population being reduced to
10,000 or even a mere 1,000 breeding
pairs
Yellowstone Supervolcano
-VEI8 Volcano
-northwest corner of Wyoming
-major features of the caldera measure
about 34 miles (55 km) by 45 miles
(72 km).
- Last eruption 640,000 years ago
(1,000 km³) DRE
- 2.1 million years ago (2,500 km³) DRE
- 4.5 million years ago (1,800 km³).
- 6.6 million years ago (1,500 km³)
Geological Activity in Yellowstone
• Scientists have revealed that Yellowstone Park has been
on a regular eruption cycle of 600,000 years
• The next eruption could be 2,500 times the size of the
1980 Mount St. Helens eruption.
• Such a giant eruption would have regional effects such
as falling ash and short-term (years to decades)
changes to global climate
• Chance of another catastrophic volcanic eruption at
Yellowstone be calculated as 1 in 730,000 or 0.00014%.
• however, this number is based simply on averaging the two
intervals. hardly enough to make a critical judgement
• Moreover, catastrophic geologic events are neither regular
nor predictable.