The Earth Flashcards
1
Q
How much of the Earth’s volume is the mantle
A
84%
2
Q
what is the core mostly made of
A
iron
3
Q
what silicate minerals is peridotite composed of
A
- olivine
- 2 kinds of pyroxene
- garnet
- plagiocase feldspar
- small quantities of metal oxides
4
Q
what elements compose over 99% of peridotite
A
- oxygen
- silicon
- magnesium
- iron
- aluminium
- calcium
5
Q
how do we know the mantle is solid
A
it transmits certain kinds of EQ waves which cannot pass through liquid
6
Q
what is mantle creep
A
- combination of heat and gravity cause mantle to flow by a slow process
- crystals slip past each other,
- atoms and ions diffuse from one place to another
7
Q
lavas pouring out of a volcano can reach temps of?
A
well over 1100 degrees C
8
Q
what are the sources of primordial heat
A
- internal heat dating back to the formation an infancy of the Earth
- kinetic energy of meteorite hails
- chemical reactions
- decay of some very ephmeral but fiercly radioactive elements
9
Q
aside from primordial heat, what are the other sources of continuing heat in the Earth’s interior?
A
- crystallisation of the core
- radioactive decay of lingering isotpes of uranium, potassium and thorium
10
Q
why is the Earth cooling
A
- it loses heat through convection into space
11
Q
electromagnetic radiation indicated a background temperature of space of…
A
-270 degrees
12
Q
% of mantle mass that is silica
A
45%
13
Q
% of basaltic magma that is silica
A
45-52%
14
Q
% of intermediate magma that is silica
A
52-63%
15
Q
% of silicic magma that is silica
A
63%+
16
Q
typical temperature of the mantle
A
1300 degreees +
17
Q
typical temp of basaltic magma
A
1100 degrees
18
Q
typical temp of intermediate magma
A
1000 degrees
19
Q
typical temp of silicic magma
A
800 degrees
20
Q
two types of melting in mantle
A
decompression melting
flux induced melting
21
Q
what % of the peridotite usually partial melting
A
1-20%
22
Q
how the mantle’s composition changed over geological time
A
mineral constituents with lowest melting points have been extracted and cooled into the crust and continents
23
Q
a typical decompression event will yield a liquid with what composition…and called what
A
mixture of pyroxene, plagioclase feldspar and a little olivine
* basaltic melt
24
Q
once basalt melt has been produced, what does the pressure do
A
pressure squeezes melt from the crystals remaining in the mantle
the melt then percolates upwards forming pools of magma which continue to rise due to lower densities
25
what % of heat and magma extracted from the Earth's mantle is from **mantle plume**
5-10%
26
what can happen when a mantle plume impinges on continents
initiate rifting like in East Africa
27
what is the Eart;s main means of cooling its infernal depths
creation of new oceanic crust at ridges and its consumption at subduction zones
28
what do black smokers do
* black smokers are chimneys which belch hot fluids charged with minerals rich in sulphur
* these nutrients feed bacteria which then nourish an entire ecosystem of creatues thriving in the stygian waters
29
stygian meaning
very dark
30
how is serpentinite ormed
* seawater percolates and circulates deep into brand new oceanic crust
* seawater reacts with the hot volcanic rock, extracting sulphur (black smokers) and hydrating olivine
* crystals accommodate a quantity of water molecules, forming the slippery green rock
31
how is the oceanic crust and seabed hydrated as it trundles along
* percolation and circulation of seawater into crust hydrating olivine and forming serpentinite
* seabed accumulates water rich clays and other waterlogged sediments
32
how does the incarcarated water percolate to the mantle at the subduction zone
* sinking oceanic plate carries the water into Earths interior
* once it reaches a depth of 100km, clay minerals, along with olivine and pyroxene crystals that had trapped seawater at the ridge, are under too much pressure to contain the water
* water is expelled and percolates into overlying mantle
33
once water at subduction percolates into mantle...now what?
* water dramatically decreases melting point of mantle causing partial melt
34
in what form is the solid component of magma
crystals of one or more minerals (ie olivine, feldspar, pyroxene, quartz)
* Generally suspended in a silicate melt
35
outline the composition of the silicate melt
* dominated by loose arrangements of silicon and oxygen atoms
* brew of other elements like Al, Na, K, Ca, Mg and Fe
* plus *volatiles* like water, CO2, sulphur and lesser amounts of halogens and trace metals
36
what would the silicate melt look like at the atomic level
* silicon and oxygen atoms bind together to form tetrahedra (Si in middle and O on 4 corners)
* tetrahedra shares electrons establishing bonds making the magma more viscous
37
gas form of magma
* bubbles of volatiles
38
how do volatile bubbles form in magma
* when mantle melts, volatiles are prefentially extracted out into new liquid
* under very high pressures they are normally dissolved into the melt
* as nascent magma ascends into crust it feels less weight - less pressure - bubbles can form - known as **exsolution**
39
what are bubbles in magma composed of
**volatiles**
* deep in crust dominated by CO2
* but as magma rises other volatiles **exsolve** - water, sulphur diozide and hydrogen flouride
40
what happens with magma at the level of neutral bouyancy
* the magma has ascended to between 3-30km deep where it has the *same density as the host rock*
* gravity no longer acts to propel it further upwards
* with sustained melting of the mantle, magmas drip feed into this zone, accumulating into magma chambers.
41
what is pumice
* Type of extrusive rock produced when lava with very high water and gas content is discharged from a volcano
42
extrusive rock
rock formed when magma rises, erupts as lava, then cools and crystallises on the earths surface
43
the more magma that collects in the magma chamber....
the greater the potential for a larger eruption
44
what is a dike and how is it formed
* cracks filled with magma that cut through the crust
* cracks initially form due to the pressure of magma in the magma pool
* if they reach the surface **fissure eruption** occurs
45
example of a fissure eruption
first phase of Ejyafjallojokull 2010
46
outline fractional crystallisation of magma and the resulting eruption
* subterranean distillation - opposite to partial melting
* magma will cool in chamber - minerals with higher melting points (like olivine) will crystallise first - this may precipitate to bottom or plaster onto walls.
* olivine is low in silica, so when it crystallises it increases the silica and volatile content in the remaining magma
* the higher volatile content will lead to bubble formation, bubbles will expand and pressurise the chamber leading to eruption
47
what do long lived magma chambers erupt (and give an example)
example - Yellowstone
* erupts rhyolites
48
silica content % of ryholites
over 73%
49
which type of magmas typically have the highest amounts of volatiles - and why
subduction zone magmas- they have derive plenty of water, sulphur and chlorine from the subducted crust
* they also reside in thicker crust for longer, so melt the rocks surrounding the magma chamber acquiring more volatiles
50
what do bubbles do to rising magma
* lower its density and increase the volumes
* accelerates the magma towards the surface
51
what does water do to rising magma - and what types of magma is this especially important to
* when water is disolved in melt, it inhibits the bonding between silica tetrahedra
* as water moves from the melt into bubbles, the tetrahedra increasingly string together into chains
* this increases magma viscosity so it moves more sluggishly
51
52
water has caused resistence to magma flow while volatiles are bubbling.... what does this mean?
if pressure is suddenly released, for example when chamber walls fail and dikes zip to surface - then **highly explosive eruption**
53
what happens when magma meets water?
* sudden production of steam and accompanying expansion can yield extremely violent eruptions
* **hydrovolcanic**
* can happen when seawater gains access to vent of island volcano - like Eyjafjallokull 2010 with glacial melt water
54
what is the eruption like with low volatile magma
* gas bubbles can escape freely leaving a slow flow of mostly melt and crystals
* it erupts peacefully in the crater or down the flanks of the volcano
* known as **effusive eruptions**
55
products of explosive and effusive eruptions
* explosive - tephra (pumice, ash, bombs - aka pyroclasts
* effusive - just lava
56
2 fundamental eruption parameters
magnitude and intensity
57
how are volcanic eruption magnitudes measured
mass or volume of erupted products (better mass as densities vary)
58
what does VEI stand for
* volcanic explosivity index
*
59
Pinatubo 1991 Magnitude scale
Me 6.1
60
how many VEI categories are there
7
61
what is the intensity of an eruption
the rate at which magma is erupted (typically measured in mass)
61
how does eruption intensity link to height of ash columns and gases
* it strongly influenecs the plume altitude
* the most intense eruptions develop ash columns over 30km above sea level
* both intensity and column height are related to the heat flux of eruption
* if intensity is greater, there is a faster rate of heat being pumped into the atmosphere - this means the volcanic cloud will ascend further
62
how does intensity infuence effusive eruptions
it strongly influences the speec and distance over which a lava flow will advance
63
What is a strombolian eruption
* type of eruption with relatively mild blasts
* typically VEI of 1-2
* consists of ejections of incandescent cinders, lapilli and volcanic bombs - to altitudes of 10s-100sm
64
what is a plinian eruption
* produces tall, sustained, ash and columns - into the stratosphere
* typically involve intermediate or silicic magmas
65
what drives the height of plinian eruption clouds
* mostly heat
* kinetic energy of the eruption amounts to much less than 10% of the thermal energy
* the nascent plume travels at 350kmph - rapidly ingests surrounding air and heats it up
* reduced density of hot air compensates for the dense as particles and pumice suspended in the plume
* once sufficient air is sucked in and heated, the plume becomes less dense than the ambient air and convects up to a *neutral density level.*
66
what factors
1. promote air entrainment for column
2. inhibit air entrainment and collapse column
1. high eruption velocities of gas charged magmas through narrow vents
2. high mass eruption rates, low exit velocities, low gas contents and wide vents
67
what is a pyroclastic current and how does it form
currents of searing mixtures of ash, rock and gases that flow under gravity of speeds up to 200km/h
* often formed from the collapse of explosive eruption columns
* can form on volcanoes with active lava domes - initiated by gravitational collapse of portions of the dome or by detonations of pressurised gas close to surface
68
outline the features of ejected pyroclasts frmom basaltic volcanoes
* They are often larger due to less fragmentation of magma in the eruption conduit
* less efficient in transferring heat energy as magma is a poor conductor - so wont scale the same heights as plinian eruption columns (less than 10km tall)
* in fire mountains - clots of lava will stay molten unlike plinian as dont release thermal energy to atmosphere
69
what are the sizes of ash, lapilli and bombs
* ash <2mm
* lapilli - up to 6.4cm
* bombs >6.4cm
70
what are the negative impacts of ash fallout
* heavy ash fall can destroy buildings - Pinatubo - ash and rain mixed to form a concrete like mixture
* crushes crops and contaminates pasture - contains flourine - which is digested by animals when eating soil killing them
* toxic - causes lung disease
71
what is an ignimbrite
pyroclastic deposits from eruptions of Me 6 and upwards
72
outline the positive impact of ash fertilisation
* volcanic soils have a good reputation for fertility
* occasional dustings provides nutrients like sulphur and selenium to soils
* in oceans it provides macronutrients and trace metals which are vital for phytoplankton growth
* potential substantial removal of CO2 from the atmosphere
73
why are pyroclastic currents so lethal
* cause heat induced shock, asphyxiation, thermal injury of lungs and burns
* incredibly fast moving so difficult to avoid
73
how are co-ignimbrite plumes (phoenix clouds) formed
* the upper parts of pyroclastic currents entrain air like plinian eruption columns due to their heat energy and turbulence
* they develop bouyant thermal plumes that punch up into the sky - **co ignimbrite plumes**
74
which lavas are more viscous
intermediate and silicic compositions
75
example of lava flo causing loss of life (which is normally rare)
Nyiragongo 1977 2002
100s of lives lost
76
possible causes of gravitational failure of volcano flank
* destabilising effects of magma intrusions into the cone
* ground shaking detonations of explosive eruptions
* local or large EQs
* heavy rainfall
77
outline characteristics of debris avalance
* rarest event of gravitational failure
* collapse of an entire sector of a volcano * enormous gravity driven rock avalanches that run out for 10s km
* can trigger an eruption like Mt St Helens 1980
78
Outline mudflows/lahars
* moving debris is water saturated and runs down drainage channels
* consists a significant fraction of clay sized particles
* Can pick up further water and debris, while dropping coarser denser material
* gradually transform into syrupy clay and water rich flows
* can also occur when lava/hot tephra is erupted onto ice or snow , when explosive eruptions take place beneath volcanic lakes, when there is intense rainfall on loose deposits
79
example of lahar tradegy
1985- nevado del ruiz in Colombia
* 23k people died
* drowning, burial, destroyed buildings
* mudflow travels 60km to the town
80
hazards from debris flow and mudflows
* burial
* property damage
* downing
* overloading river systems leading to floods
* can take centuries for landscape to readjust
81
how can volcanoes cause tsunamis
* landslides and avalances - displaced material drops into sea
* pyroclastic currents hitting the water
* collapse of the crust above a magma chamber during caldera formation on an undersea volcano
* hydrovolcanic explosions - caused by seawater entering eruption vent
81
what is a caldera
* large depression formed when a volcano erupts and collapses
* when large volumes of magma are erupted over a short period, structural support for rock above magma chamber is gone - leading it to collapse
82
what is the most important volcanic gas in climate change
sulphur
83
at what altitude does the statosphere begin
11-17km
84
how high did the pinatubo cloud peak in 1991
35km above sealevel
85
what happens to the amount of silicate ash in the stratosphere after an eruption
immediately there will be significant quantities of silicate ash lofted into the stratosphere, but this will sediment in a matter of days-weeks
86
what happens to gaseous SO2 erupted
* it oxidises and forms sulphuric acid aerosols in the stratosphere
* once most has been converted, little more aerosol is formed and the total stratospheric aerosol load decreases as particles subside into the troposphere
* they are then rapidly deposited to the surface by rainfall and other process
87
height of the tropopause
10km in the poles and 18km in the tropics
87
settling rate for small sulphur aerosols
4 months for every 10km
88
what do aerosols do to solar radiation
scatter incoming UV and visible radiation, directing some back into space and some sideways and forwards. Some is also aborbed
89
what is needed for the aerosol to have warming outbalance cooling. and what was pinatubo
aerosols radius should exceed 2 thousands of a mm. pinatubo was 0.5 thousands.
90
what is the tropopause
boundary between stratosphere and troposphere
91
why is tropopause higher at equator
the equator is warmer, so currents of air expand the thickness of the troposphere at poles
92
outline the stratosphere
* extends from 6-20km up to around 50km
* **t****emperature increases with height**. heat is produced in formation of ozone
* warmer air is therefore above cooler air, meaning **no convection **as no upwards vertical movement of gases
* bottom of layer is readily seen with tops of **cumulonimbus** clouds
* transition to troposphere is the **tropopause**
93
outline the troposphere
* almost all weather occurs in this region
* 6-20km high
* density of gas decrease with height, thus also temperature
94
what does LIP stand for
large igneous province
95
which eruption serves as the foundation on understanding climatic impacts of eruptions
pinatubo 1991
96
How long can aerosols persist in the stratosphere
couple of years
97
how long can be the impact on climate of gases and particles in the stratosphere and troposphere
* stratosphere 1-3 years
* troposphere 1-3 weeks before being pulled back by precipitation
98
how much SO2 released into Stratosphere by Pinatubo
18 megatonnes
99
how much was the albedo of Earth increased by in 1991 Pinatubo
5%
99
how much was direct sunlight cut by Pinatubo 1991
25-30%
100
how much did temperatures cool by after pinatubo 1991
0.5 degree C
101
when did the net flux of energy return to normal levels after pinatubo
2 years later in 1993
102
how do volcanic eruptions link to ozone depletion
aerosols produced by major erptions accelerate ozone destruction. Particles provide a surface where chemical reacitons can take place, enhancing chlorine driven ozone depletion.
103
what are LIPs
large igneous provinces are areas of high volume magmatic acitvity which can span as large as millions of km^2 occuring with a maximum life span of 50myr.
104
atleast four of the 5 mass extinctions....
overlap in the time of LIP events
105
how long did the sulphur injection from the Siberian traps last
100-200years
106
how do LIPs cause warming
emissions of GHGs like CO2
107
why was photosynthesis encouraged in some regions after Pinatubo 1991- despite cooling
explain the `positive feedback`
* reduction in direct sunlight reaching the surface - many plants dislike very intense light
* increase of scattered light in the sky - which penerates more vegetation canopy than direct sunshine thus more leaves
* means we saw a positive feedback with more carbon sink, furhter pushing cooling
108
why was coral killed after pinatubo 1991
cool air temps in Red sea enhanced mixing in water column, bringing nutrients to surface, stimulating algal blooms
* waters turend green with chlorophill, shading corals and hampering water. stagnated water built up hydorgen sulphide, killing much of the coral.
109
how can volcanic eruptions deplete ozone
* sulphuric acid particles provide surfaces where ozone destroying reactions can occur
* chlorine is trasnformed from stable compounds like hydrogen chloride to reactive forms like `hypochlorous acid` which destroy ozone
110
why might humans still be a factor of volcanic eruption ozone depletion
* most of the stratospheric chlorine in Pinatubo that reacted was sources from CFCs
* chlorine erupted from a volcano is in the form of hydrogen chloride, which dissolves into water and moist air
110
what is the relationship between sulphur solubility and silica content of magma
inverse. basaltic magmas contain 0.1% by mass of disolved sulphur while silicic magmas contain as little as 0.002%
111
what type of magma are nearly all explosive eruptions
silicic
112
what is an oxidising agent
chemical species that will accept electrons from another species - for example iron
113
what is the relationship between sulphur dissolving and oxidiation
magmas can take in more sulphur when highly oxidising or highly reducing
114
factors making magmas sulphur rich
* silica content
* oxidising/reducing
* temperature and pressure
115
what is the saturation effect of sulphuric acid in stratosphere
* general trend that bigger eruptions and more sulphur rich magmas will cause stronger perturbations to climate
* however, more sulphur in stratosphere means larger particles will form - thee are less effective in scattering sunlight and drop out of atmosphere faster
* the atmosphere is saturated with injections a few times larger than Pinatubos
116
whats the relationship between injection height of sulphur and climate impact
* if column is confined to the troposphere then the atmospheric processing of the S is spred up due to rapid rain deposition
* more explosive eruptions will loft S gases to the stratopshere where they can generate climatically effective aerosol
117
which is the least best understood type of volcanism
hotspot
118
temperature of magmas at
* hotspots
* subduction zones
* 1200 degrees
* less than 1000 degrees
119
axes on the phase diagram
x = temperature
y = pressure and depth
120
what is the rate of movement of convecting peridotite
10-20cm a year
121
where is peridotite thought to come from in the hotspot plumes
much deeper than ocean ridges, near the boundary with the outer core
122
* mid ocean ridges
* subduction zones
* hotspots
**explain what happens to the geotherm and solidus at each to form magma**
* mid ocean ridge - lower pressures as peridotite rises mean the geotherm shifts to cross solidus
* subduction zones - solidus crosses geotherm as flux of water changes composition and lowers melting point
* hotspot - higher mantle temperatues means geotherm shifts to cross solidus
123
3 major components of magma and what does this mean for viscosity
* crystals
* glass
* gas
the balance between these 3 determines the viscosity and behaviour of magma.
123
more silica means magma is more
viscous!
124
what are the most explosive magmas
rhyolitic magma
125
what is the most explosive type oferuption
plinian
126
what does an eruption need to generally be to cross the tropopause in the tropics than mid to polar latitudes
explosive erption needs greater intensity at tropics, as tropopause is higher.
127
what are the two factors that counteract climatic impact of high latitude eruptions
* the biggest impact of aerosols is scattering sunlight back into space - but there is less solar energy to intercept at high latitudes
* atmospheric circulation means winds at altitude blow from polewards from tropics - therefore eruptions at high latitudes will go against the temperature gradient and not flow to the southern hemisphere
128
why does an eruption cloud rise higher in a humid atmosphere
* the latent heat released when water vapour entrained in plume condenses out and freezes on altitide - **additional source of thermal energy to drive plume ascent**
129
how does timing of the year affect ITCZ - and what does this mean for eruptions
* shifts north of Equator during N hemisphere summer and south during winter.
*
130
landforms found on oceanic oceanic boundary
deepsea trench and volcanic island arc
131
example of mountain belt found on convergent plate boundary
the andes
132
how deep does the marianas trench reach...and what type of boundary is it
* over 11km deep, oceanic-oceanic convergence
133
example of island arcs
Aleutian islands off Alaska.
134
what are the x and y axis on the phase diagram
x = temperature
y = pressure
135
define geotherm
the geothermal represents how the Earths internal temperature changes with depth (pressure)
136
define solidus
the solidus is the line showing the temperature and pressure at which a substance begins to partially melt
137
where does the geotherm kink
lithosphere-asthenosphere boundary
138
what is the rate of temp increase in the lithosphere
25-30 degrees / km
139
how old are the oldest volcanic rocks
2.9 bilion years
140
what is the least understood type of volcanism
hotspot!
141
temp of magma at hotspots and subduction zones
1200, below 1000
142
what moves solidus/geotherm during subduction
solidus
143
what determines the viscosity of magma
the balance of 3 components:
solid crystals, liquid and gas
144
what does more silica do to magma viscosity
silica tetrahedra polymerise together and make long chains
145
why does higher viscosity magma make explosive eruptions
it is more polymerised and dense, bubbles cannot move around the melt. the gases expand and expand fragmenting the magma and explodign
146
3 types of effusive eruptions
stormbolian, fissure and Hawaiian
147
3 types of explosive magmatic eruptions
pinion, vulcanian, pelean
148
what type of eruption happens at mid ocean ridges
phreatomagmatic.
149
how is magnitude of an eruption measured
total mass/volume of deposit/lava
150
how is eruption intensity measured
eruption rate in mass/volume per unit time
kg/s
151
3 ways to quantify eruptions
intensity, magnitude, duration
152
what magnitude was pinatubo
6
153
what is volcanic degassing responsible for in the first place
making the atmosphere breathable in the first place
154
how does monitoring gas help predict eruptions
magma rising will release gases, so the greater presence of gases indicates magma
155
define lava lake
large volume of molten lava, usually basaltic, contained in a volcanic vent, crater or broad depression.
156
what are lava domes and how are they foremd
circular mound shaped protrusion resulting from the slow extrusion of viscous lava from a volcano
157
how does a Strombolian eruption occur
when there is a bit of gas in the magma. occurs sporadically in open vent volcanoes where the vent is filled with magma.
large bubbles of gas coalesce together and then rise and explode
158
how tall are lava fountains
up to 2km tall
159
what do lava fountains produce
scoria
160
what happens and what is formed when hydrovolcanism happens on land
explosive eruption creating tuff cones
161
where does subglacial volcanism occru
iceland
162
what is a tuya
flat topped steep sided volcano formed when lava erupts through a thick glacier/ice sheet
163
what type of eruption was Vesuvius 79
plinian
164
how long are pinion eruptions
hours to days
165
how tall are eruption clouds of plinian eruptions
known to be as tall s 40km
166
where is the tropopause located at poles and tropics
20km at tropics
10km at poles
167
largest eruption of 20th cent
pinatubo 1991
168
how wide was the cloud of pinatubo
100km
169
impacts of ash fallout
respiratory damages
roof collapse
170
what are pyroclastic flow
fast flowing currents of rock, ash and hot gas produced during eruptions
171
how fast can pyroclastic flows be
200km/hr +
172
explain the formation of pyroclastic flows
explosive eruptions eject pyroclastic material, which ascends due to its higher temperature and bouyancy
due to gravity the cloud becomes denser and collapses. this triggers it to cascade down the sides of the volcano, with the Material above pushing the lower material downhill
173
how are mudflows caused and what are they also called
lahars
the large accumulation of ash that is unconsolidated, followed by rain.
174
where is pinatubo located
Luzon, Philippines
100km from manilla
175
when did pinatubo start and climax
June 12th
June 15th
1991
176
what landform was created by pinatubo
caldera , 2km wide!
177
how high was the tropopause above pinatubo
17km
178
how much SO2 was released by pinatubo
20 million tonnes
179
what happens to the SO2 in the atmosphere
it reacts with water and is oxidised forming stratospheric solid sulphate aerosol
180
what is the correlation between sulphur aerosols and visible light
the size of aerosols is similar to the wavelength of light
0.4-0.7 microns
181
why was it significant the Pinatubo eruption happened near the equator
the aerosol clouds could spread in both hemispheres
182
what are the primary gases given by eruptions
CO2 and H2O
183
how long before the ash fallout from explosive eruption
2-3 weeks
184
how long can fine ash last in the stratosphere and how small it is
1 micron, very fine
for up to a year
185
after the eruption what happens to materials that only reach the troposphere
will be washed out, including gases
186
as a consequence of global cooling after pinatubo what happened at the tropics
drought
this affects the monsoon system
187
aside from Pinatubo what other eruption recently caused cooling
el chichon
188
what conditions are needed for an eruption to cool the climate
large emission of SO2
preferably explosive to get the SO2 into the stratosphere
tropical latitude to spread in both hemispheres
should happen in summer for greater impact
189
why does eruption size not necessarily correlate with climate effect
big eruptions may have magma high in gas, so there is not much sulphur
while smaller ones may have more sulphur
190
how many years for temp to recover after pinatubo
5
191
how many years for temp to recover after toba
10
192
how much did temperatures drop by toba eruptions
12 degrees
193
how do we know of past eruptions
ice cores!
we look at fine ash (which settles after a year )
as well as sulphur (Which settles 2/3 years )
spikes in acidity = eruption
194
how may halogens affect climate from eruptions
chlorine, bromine, iodine from magma
they react with ozone and cause catalytic destruction
195
where have we studied halogens in ozone
el chichon 1982
196
what does LIP stand for
large igneous province
197
what type of eruptions form LIPs
effusive
198
where do LIPs form
over hotspots
199
how long do LIPs take to form
centuries to millenia
200
what are the LIP magmas rich in
CO2, sulphur and chlorine
201
how did Siberian traps effect end permian
triggered significant warming due to the continuous injection of SO2 and greenhouse gases into the troposphere over millennia
202
what can most mass extinctions be linked to
LIPs
203
how did samalas eruption effect Europe
led to a colder few years from 1257 leading to famine and bad harvest
1.5million died
204
how did pinatubo affect the ocean
acidification
205
define LIP
exceptional volcanic events in Earths history characterised by large total volume of mainly magic magma erupted in a brief period of time (less than 1 million yrs)
206
compare the volume of magma
pinatubo and siberian traps
5 km3
over 15 million km3
207
what are the characteristics of LIPs
* iron and magnesium primitive rich lavas
* millions of km3
* from potentially a focus source/fissure
* presumed to be caused by Giant mantle plumes
208
how is tephra dated
argon argon dating
209
how are LIPs formed
* formed due to anomalies within interior
* deep plumes from the mantle rise towards the surface
* at the top, the mantle melts thorugh decompression melting
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how may Siberian traps have caused end permian extinction
ozone depletion by halogens - led to over 1000 as much UV radiation
greenhouse gases
all led to rapid warming
211
aside from ozone depletion, list the other ways LIPs may have caused large scale species extinctions
oceanic anoxia
ocean acidification
sea level changes
toxic metal input
essential nutrient decrease
212
how is the cenozoic cooling thought to be caused
Mountain uplift all across the earth
213
what is key to establish links of cause and effect on whether LIPs impacted climate
geochronological precision
214
what Does VEI stand for
volcanic explositivity index
215
how much ash and pumice was expelled by pinatubo 1991
10 trillion kg
216
what is the average length of a volcanic eruption
1 month
217
how do ice cores indicate former volcanic eruptions
spikes in electrical conductivity and acidity are caused by sulphur fallout
from major eruptions
218
DVI and VSI
what are they
dust veil index
developed by Hubert lamb, it looks at how dust vails affected radiation reaching the earths surface
volcanic sulphur index
measures eruptions based on tonnage of sulphur ejected
219
how do local people view Mauna Kea
home to the goddess Pele, she lives in side and can create or destroy land, can have sudden rage
Hawaii is her land and they should respect her. they offer berries to her
220
which types of magma are higher in gas -basaltic or silicic
silicic
221
why is pinatubo so important for understanding climate impacts
it was because it could be monitored by satellites
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