Hazardous Earth Flashcards
What is a moho ?
mantle - crust boundary is marked by this
what two layers is the upper mantle made from ?
asthenosphere
lithosphere
what is the asthenosphere ?
layer that extends from 100km to 300 km solid but flows under a pressure
what is the lithsophere ?
lies immediately above the asthenosphere
rigid layer sandwiched between crust and astenosphere
what is the thickness of the crust ?
continental =
mean = 35km
min= <30 km
max = 70km
oceanic - 5-10km
what is the thickness of the mantle ?
to a depth of 2900km
what is the density of the crust ?
continental = 2.6-2.7
oceanic = 3.0
what is the density of the matle ?
3.3 @moho
5.6 @core
what is the mineral composition of continental crust ?
mainly granatic, silicon , aluminium
what is the mineral composition of the oceanuc crust ?
mainly basaltic, silicon and magenisum
what is the mineral composition of the mantle ?
rich in magnesium and iron
who invented the continental drift theory ?
Alfred Wegener
when did Alfred Wegener invent the continental drift theory ?
1912
what is the continental drift theory ?
carboniferous period, 250 million years ago, large single continent , pangaea existed
slowly broke apart into two land masses
moevemtn continued to the present day as the continents seperated and spread across globe.
why was wegener’s theory rejected ?
rejected by academic geologists who dismissed the evidence , preffering their own dominant ‘fixed earth’ paradigm
what is the geological evidence of the continental drift theory ?
fit of continents like S america and africa
evidence from about 290 million years ago of the effects of contemporaneous galciation in S Africa, Australia, S America, India and Antartica . Suggesting that these land masses were joined at this time, located close to south pole
- mountain chains and some rock sequences on either side of oceans show great similarity e.g. NE Canada and N Scotland
what is the biological evidence of continental drift theory ?
-similar fossil brachiopods (marine shellfish) found in Australian and Indian limestones
- similar fossil animals found in S America and Aystralia , especially marsupials
- fossil from rocks younger than the carboniferous period, in places such as Australia and Inidia, showingfewer similarities, suggesting that they followed different evolutionary patterns
what is another word for a divergent boundary ?
constructive
what is another name for a convergent boundary ?
destructive
where do divergent plate boundaries occur ?
locations where plates diverging (moving apart) are rising through the asthenosphere and forcing its way to the surface
what is especially notable at a mid ocean ridge ?
plumes of rising material
what is a mid ocean ridge ?
most spectacular relief feature on the planet but remain hidden at an average of 2.5km below ocean surface
very long chains of mountains - in places 3000m above the sea bed
added together these submarien mountain chains have a comibned length of 60,000 km
are mid ocean ridges contionuos or non-continuous ?
not continuous
how are frequent intervals of mid ocean ridges broken into segments ?
by transform faults
what is palaeomognatism ?
ancient record of changes in Earth’s polarity is known as this
echo sounders used to locate submariens for the first time, the existence of the Mid -atlantic ridge
what is sea floor spreading
moves material across the ocean floors as a ‘conveyor belt’ operating on each side of the mid -ocean ridge
what is the prediction of the ageof sea floor rocks ?
ocean - rocks would get older the further one was from the mid-ocean ridge
what was the actuality of the age of sea floor rocks ?
cores also sjwed that nowehere i the oceans was rock older than 200 million years, this confirmed that the ocean crust was constantly recycles over this period
what is a transform fault ?
displace mid ocean ridge laterally
- tens or hundreds of km
- as they slip - energy is released in form of earthquakes
- volcanoes = absent
why are volcanoes absent at mid ocean ridge ?
bocs conservative margin
what is the rate of spread of a fast spreading boundary ?
up to 16.5 cm/yr
what is the rate of spread of a medium spreading boundary type ?
5-10 cm per year
what is the rate of spread of slow spreading boundary type ?
2-3 cm per year
what type of landforms are there at a fast spreading boundary ?
broad and smooth mountain shains , no centra rift valleys
what type of landforms are there at medium spreading boundary ?
poorly defined central rift valleys , relatively smooth mountain shains
what type of landfroms are there at slow spreading boundary ?
steep slopes to mountains chains , clearly defined central rift valleys
give an example of a fast spreading boundary ?
east pacific rise (pacific and Nazca
what is an example of a medium spreading boundary ?
galapagos ridge (just south of the Nazca and Cocos plate boundary )
what is an example of a slow spreading boundary ?
mid - atlantic ridge (N AMerica and Eurasia and S America and African plates )
what is pillow lavas ?
magma erupting directly on to the sea bed is cooled rapidly , forming rounded mounds.
how is pillow lava formed ?
magma rises - pressure reduces - liquifies
how are underwater rift valleys formed along mid-ocean ridges ?
overlying rocks are forced upwards as the lithopshere is plaes under stress and eventually fractures
how was iceland created ?
north atlantic - extrusion of magma has been so great is has created the world’s largest volcanic island -
what are black smokers ?
superheated jets of water somethimes re-emerge on the ocean floor containing metal sulphides
what is good about black smokers ?
support unique and highly specialised organisms and ecosystems
what are rift zones ?
not confined to the ocean floor also occur on land and in part explain how continents can break up
what must be a thin consistency for rifting to occur ?
continentla curst
give an exmaple of rift stretching ?
from Red Sea northwards to Turkey
what is a graben ?
here , crust has been uplifted and stretched causing faulting and forming a sunken valley known as a graben
how was the red sea formed ?
rift widened, magma erupted at the surface and eventually the rift valley sunk below sea level
What is the lowest point of the Dead Sea ?
-400m which is the lowest point on the continental surface
what are the three types of convergent boundaries ?
oceanic continental
oceanic oceanic
continental continental
what happens at the oceanic - continental boundary ?
different densiities - when oceanic and continental converge the denser oceanic plate is forced under continental = SUBDUCTION
what does subduction cause ?
a deepening of the ocean at the plate boundary and forms an ocean trench
what are some features of an ocean trench ?
depths of 6000- 11,000 m
long
narrow
asymmetric
steepest side twoards continent
depressions
what is slab pull ?
oceanic crust descends into te asthenosphere , pulling the rest of the ocean plate with it in a process called slab pull
how is an ocean trench formed ?
leading edge of the overiridng plate is buckled
how are mountain chains formed ?
layers of sediment and sedimentary rock develops on oceanic plates adjacent to continents
As oceanic plate converges on continental plate, these sediments and rocks crumple, fold and are uplifted along the leading edge of the continental plate
ALSO - Cntinental crust is buckled and uplifted , and significant amounts of molten material are injected into it.
what is an example of mountain chains ?
Andes, S America
what degrees is oceanic plate subducted at (oceanic - continental) ?
between 30 and 70 degrees
when can earthquakes occur (oceanic-continental ) ?
as it descends, comes under pressure and friction
faulting and fracturing occur in the Benioff zone , releases lots of energy = earthquakes
what happens in oceanic oceanic ?
slightly older and denser one subducts other , creating a trench
how are island arcs formed ?
dehudration takes place cause partial melting of the matle wedge . this magma rises 2 surface and forms chains of volcanic islands
how was the island arc of Antilles formed ?
central atlantic , N american plate subducted beneath the smaller caribbean plate forming antilles
are large earthqaukes common at oceanic-oceains ?
common
at pacific ocean how many of earthquales occur here (oceanic-oceanic) ?
largely rimmed by either convergent or conservative (transform) boundaries , about 80% of all earthquakes , and many volcanoes located here
what happens at continental continental ?
two plates converge - little, if any subduction takes place
bcos they have similar denisities
how was the alps created ?
collision of african and eurasian plates over the past 40 million years has created alps
what happens at conservative plate margins ?
at some places - tectonic plates neiuther diverge or converge but rather slide past each other
what is volcanic activity like at conservative plate margins
absent
cos no subduction takes place
do earthquales happen at conservative plate margins ?
frictional reistance to movement along the plate boundaries often causes the build-up of pressure. From time to time , these pressures cause rocks to fracture releasing enormous amounts of energy as the pressure is released , causing earthquake s
what are examples of conservative plate margins ?
cali, N America and pacific plates
where are explosive volcanoes loacted ?
convergent plate boundaries
where are effusive volcanoes located ?
divergent plate boundaries
what type of lava do explosive volcanoes have ?
rhyolite (more acidic)
andesite (less acidic)
what type of lava do effusive volcanoes have?
basaltic
what are the lava characteristics of explosive volcanoes ?
acid (high % of silica ) , high visocity, lower temp at eruption
what are the lava characteristics of effusive volcanoes ?
basialtic (low % of silicon ), low visocity , higher temp at eruption
what is the style of eruption at an explosive volcano ?
violent bursting of gas bubbles when magma reaches surface , highly explosive, vent and top of cone often shattered
what is the style of eruption of effusive volcano ?
gas bubbles expand freely, limited explosive force
what materials are erupted in explosive volcano
gas, dust , ash , lavabombs , tephra
what materials are eruptes in effusive volcano ?
gas, lava flows
what are the frequency of explosive eruptions ?
tend to have long periods with no activity
what are the frequency of effusive eruptions ?
tend to be more requent, an eruption can continue or many months
what is the shaoe of an explosive volcano ?
steep sided strato volcano , caldera
what is the shape of effusive volcano ?
gently sloping sides , shield volcanoes, lava plateaux when eruption from multiple fissures
what is an icelandic lava eruption ?
characterised by persistent fissure eruption
large quantities of basaltic lava build up horizontal plains
what are Hawaiian eruptions ?
more noticeble central activity thsn icelandic . Runny, basaltic lava travels down the sides of the volcano in lava flows
gases escape easy , ocassional pyroclastics
what are strombolian eruptions ?
characterised by frequent gas explosions which blast fragments of runny lava into the air to form cones
Very explosive eruptions with large quantity of pyroclastic throughouts
what are vulcanian eruptions ?
violent gas explosions blast out plugs of sticky or cooled lava. Fragments build up into cones of ash and pumice . occurs when very viscous lava which solidifies rapidly.
often the eruption clears a blocked vent and spews large quantities of volcanic ash into atmosphere
what are vesuvian eruptions ?
very powerful blasts of gas creating ash clouds high into sky
- they are more violent tan vulcanian eruptions
ava flows occur
what are plinian eruptions ?
gas rushes up thru sticky lava and blasts ash and fragments into sky in huge explosion
violent eruptions - large clouds of gas and pyroclastic clouds can rush down slopes
part of volcano may be blasted away
what is another name for strato volcanoes ?
composite cone volcanoes
what are strato volcanoes made of ?
layers of ash and acid lava
what type of profiles do strato volcanoes have ?
concave symmetrical profiles
what do strato volcanoes contain ?
complex internal networks of lava flows which form minor igenous features such as skills and dykes
what happens with acid magma and tsrtao volcanoes ?
acid magma doesnt flow as easily
vents are often fielled with a mass of solidified magma - prevents magma from tising freely from depth -
so,,, enormous pressures can build up inside a volcano until it erupts
what is a caldera /?
volcanic craters more than 2km in diameter
how do calderas form ?
explosive eruption destroys much of the cone and underlying magma chamber is largely emptied
how large did the eruption of krakatoa in 1883 leave a caldera ?
7km wide
what are food basalts >?
when basic magma erupts from multiplw fissures, vast areas can be covered by free-flowing lava
what is an example of a lava plateaux ?
deccan plateau - central india , covers more than 500,000 km squared
what is another name for a hot spot ?
intre plate volcanoe
what is a hot spot ?
fixed area of intense volcanic activity where magma from a rising mantle plume reaches the Earth’s surface
how did hawaiian island chains form ?
they lie at centre of the pacific plate, thousands of kilometres from nearest plate boundary - so formed due to existence of hot spots
what is a super volcano ?
erupts more than 1000km cubed o material in a single eruption event
what is yellowstone supervolcano ?
wyoming
caldera = 75km diametre
what is the impact of supervolcanoes ?
Very high magnitude events is deduced from the extent and depth of ash alyers and their impact on plant , insect and animal species
what are the two key factors of measuring and assessing volcanic activity ?
magnitue
intensity
what is magnitude ?
amount of material erupted
what is intensity ?
speed at which material is erupted
what is VEI ?
volcanic explosivity index - combines magnitude and intensity into a single number on a scale of 0, the least explosive , to 8, the most explosive
Each increase in number represents nearly a ten-fold increase in explosivity
what type of lava flow is a basaltic lava flow ?
free flowing and can run considerable distances
what lava flow happened in Hawaii, july 2015 ?
lava flow extended for 20km before stopping in August the same year a flow was reported to have covered 800m in a day
what is an acidic lava flow like ?
rhyolite and thick and pasty so dont flow easily
what does lava flow destroy ?
eveyrthing in path will be burned, buried or bulldozed.
Destory infrastructure , property and crops, lava flows, rarely cause injuries or fatalities
what is a pyroclastic flow ?
combo of very hot gases (500 degrees plus) , ash and rock fragments travelling at high speed (100km/h)
Follows contours of ground and destroy everything in their path
what will happen if you inhale pyroclastic flow ?
instant death
what happened at pompeii (pyroclastic flow)?
Overhwelmed by pyroclastic flow from Mount vesuvius in AD 79
WHAT IS TEPHRA ?
describes any material ejected from a volcano in the air
Ranges in size from very fine ash to large volcanic bombs (>6cm across).
Also lighter debris = pumice
what does tephra destroy?
buries farmland in layers of ash and destroying crops
- transport distrupted both on ground and air
Buildings = collapse = weight of accumulated ash and people with respiratory diseases cant breath
how did tephra affect Eykafjallajokull ?
Apr 2010 - cancellation of 100,000 flights
what gases do volcanoes emit ?
CO2 , CO, SO2
WHAT is the impact of gases from volcanoes ?
deadly threat to human populations
so2 combines with atmospheric water, acid rain = produced
damage crops and pollute surface water and soils
what is a lahar ?
type of mudflow with consistency of wet concrete
Snow and ice on volcano summit melt during an eruption and flow rapidly down the cone
Rock fragments large and small, as well as ash and soil are mixed together
what speed do lahars travel at ?
up to 50km/h
what do lahars destory ?
everything in its path is destroyed or buried under thick layers of debris
what happened with lahars at eruption of nevado del ruiz ?
1984 - eruption of nevado del ruiz , colombian town of armero , overwhelmed by lahars, resulting in death of 23,000 people
what is volcano caused floods ?
volcanic eruptions beneath an ice field or glacier cause rapid melting
what is a jokulnlaup ?
ICELAND - several active volcanoes lie under the vasnajokull ice accumulate until they find an exit from under the ice.
resulting torrent of water is known as a jokulnlaup
what is a tsunami ?
violent eruptions of some island volcanoes can cause massive displacement of ocean water and tsunami waves capable of travelling at speeds of up to 600km/h.
Deep water = height that is usually less than 1m and very long wavelength up to 200km.
Approaching shore, tsunami waves increase rapidly in height AND WHEN THEY BREAK transfer vast amount of energy and water along the shore and island
what was the tsunami at krakatoa ?
1883 - drowned 36,000 people
how did the eruption of supervolcano toba , indonesia impact long term ?
climate change
led to reductions in global temp as ash blocked sunlight from reaching earth’s surface
how does eruptions impact climate chnage
?
emitt large quantaties of ash
release of so2 - added to cooling ‘mixed with water in atmos so2 forms sulphuric acid - which reflects insolation
What are the impacts of SO2 being released from a volcano ?
adds to cooling
Mixed with water in the atmosphere it forms sulphuric acid, which reflects insolation.
Where is Lake Nyos ?
Cameroon, West Africa
What is Lake Nyos ?
one of a number of deep lakes that occupy volcanic craters in Cameroon
2km wide and 200m deep
what happened in Lake Nyos in 1986
1700 people and all animal life in the area around volcano were asphyxiated
The cause was a leak CO2 from a volcanic crater lake
Gas had built up at the bottom of the lake after being emitted from the underlying magma chamber
Co2 is dense gas and when it escaped it flowed down volcanic slopes as a 50m thick ground-hugging layer travelling at about 70km/h.
Lake Nyos - possible explanations to how co2 escaped the lake ?
Deep movement of magma
an earthquake
change in water temp in lake
strong winds stirring up the lake waters , like shaking a fizzy drink
what is an earthquake ?
represent the release of stress that has built up within the Earth’s crust caused by tension, compression or the shearing of rocks
what happens in an earthquake ?
A series of seismic shock waves originate from the earthquake focus, the location where the stress is suddenly released
where is the epicentre ?
immediately above the focus . at the earths centre
what are some earthquakes preceded by ?
a number of fore-shocks
If the fore shocks have the same P adn S wave profiles, they may be a signal that a large event is likely , allowing time to warn a population
what happens after the main quake ?
after shocks which gradually reduce in intensity
where is earthquake activity concentrated in ?
Mid ocean ridges
Ocean trenches and island arcs
Collision zones
Conservative plate margins
why do earthquakes happen at mid ocean ridges ?
tensional forces associated with spreading processes and subsequent faulting and rifting
why do earthquakes happen at ocean trenches and island arcs ?
compressive forces associated with the subduction of one plate below another
why do earthquakes happen at collision zones ?
compressive forces associated with the grinding together of plates carrying a continental crust
why do earthquakes happen at conservative plate margins ?
shearing forces associated with the intermittent movement of one plate past another
Where can Seismic waves travel ?
both along surfaces and through the layers of Earth
what are primary (p) waves ?
fast-travelling, low frequency compressional waves
They vibrate in the direction in which they travel
what are secondary (s) wave s?
half speed of p waves
high frequency
They vibrate at right angles to the direction in which they travel
what are surface (l) waves ?
slowest of the three
low frequency
Some have rolling movement that moves the surface vertically, while others move the gorund at right angles to the direction of moevment
What do the three waves travel through ?
L = outer crust only
S = cant pass through liquids
P = travel through earths interior (both solids and liquids)
What are shallow focus earthquakes ?
Surface down to 70km
cold, brittle rocks resulting from fracturing of rock due to stress within crust
Very common
Many releasing only low levels of energy
other high energy shallow quakes are capable of causing severe impacts
what are deep focus earthquakes ?
70 to 700km
poorly understood
With increasing depth, pressure and temps increase to veyr high levels
Minerals change type and volume, which may contribute to a release of energy
Likely that dehydration of water in subducting plates play a significant role in these events, but scientists continue to evolve their ideas about these less freuquent but often powerful quakes
What is Richter scale ?
developed in 1935
Uses the amplitude of seismic waves to determine earthquake magnitude
Scale is logarithmic so each whole number increase in magnitude represents a ten-fold increase in the amplitude of the seismic wave
This represents a 30-fold increase in release of energy
What are the negatives of Richter scale ?
no upper limit
not used to express damage
What does the modified mercalli scale measure ?
measures earthquake intensity and its impact
It relates ground movement to impacts that can be felt and seen by anyone in the affected location
Qualitative assessment based upon observation and description
What are scientists increasingly using ?
Moment Magnitude Scale
What is the Moment Magnitude Scale ?
Measures the energy released by the earthquake more accurately than Richter scale
- The amount of energy released is related to geographical properties such as the rock rigidity, area of the fault surface and amount of movement on the fault
Is the moment magnitude scale logarithmic ?
Yes
Why is the moment magnitude scale the most accurate ?
Uses the amount of physical movement vaused by an earthquake , which is a direct function of energy
what are the negatives of Moment Magnitude Scale ?
Not used for small earthquakes
What would earth look like if there was no earthquakes ?
landscape would be more or less flat given the combo of gravity and erosion/weathering/transport.
What can earthquakes create ?
entire mountain chains such as Himalaya-Karakoram Range in Asia
What did the northward dirft of India into Eurasia and the subsequent continental collision lead to ?
Compex pattern of folding and faulting of rocks
What is the Tibetan Plateua ?
Averaging 4500 m above sea level it covers an area of 2.5 million km squared
Major fault systems are evident in the rocks and these indicate considerable movement
What do rift valleys show ?(earthquakes
The rift valleys along mid-ocean spreading ridges, in East Africa and Iceland, are also evidence of the effects associated with earthquakes on the morphology of the Earth’s surface
What do inward-facing fault scarps or escarpments of rift valleys mark ?
The location of faults caused by tension and compression within the crust.
what are rift valleys altered by ?
weathering and erosion
What happens to fault scarps over time ?
They are worn away
They can even dissapear under accumulated sediments
Between 2000 and 2015 how many people were killed by earthquakes ?
800,000- 900,000
What does the severity of ground shaking depend on ?
- earthquake magnitude
- distance from the epicentre
- local geology
Where will experience extreme ground shaking ?
Locations that are close to the epicentre of a high-magnitude earthquake and where the surface layers are relatively unconsolidated and have a high water content
What do ground moevemtns cause ?
Dsipalcement of rocks along fault lines can rip apart pipelines and sewers
ever rigid structures such as railway tracks and roads, and cause buildings to collapse
What can the displacements on the surface also cause ?
disrupt natural drainage
diverting streams and rivers and affecting the movement of groundwater in aquifers
Can have serious implications for public water supplies and irrigation for agriculture
What is liquefaction ?
When an earthquake strikes an area with surface materials of fine grained sands, alluvium and landfill with a high water content, the vibrations cuase these materials to behave like liquids
they loose their strength and structures tilt and sink as foundations give way
when was liquefaction a major issue ?
Kob earthquake
Much of the port had been built on reclaimed land in Osaka Bay
Just under 200 berths in the port were destroyed, affecting Japanese Economy and trade worldwide
What can ground shakign and liquefaction cause ?
SLope failure
Where is especially vulnerable to slope failure ?
DSteep slopes in Mountainous regions like Himalaya-Karakoram range
Their vulnerability is increased by deforestation and heavy monsoon rains , so that even small tremors can trigger landslides
What did the Nepalese earthquake of 2015 trigger ?
Large number of landslides and avalanches caused by ground shaking
What are the negative impacts fo landslides ?
Block transport routes in mountainous regions where accessibility is already difficult
Movements of rock and soil on slopes can also block rivers
These natural dams create temporary lakes, which can threaten areas downstream with fllooding
This happened in Sichuan 2008
What happens if an earthquake creates a landslide on slopes above a reservoir ?
The displacement of water and the waves generated could weaken and overtop the dam.
Northern Italy 1963- collpase of a hillside above the Vaiont reservoir, generating a 100m wave which drowned 3000 people
How are tsunamis caused by earthquakes ?
Underwtaer earthquakes can cause the sea bed to rise vertically
Thsi displaces the water above , producing powerful waves at the surface which spread out at high velocity from the epicentre
What is the local highest of a tsunami affected by ?
The shape of sea bed and coastline
What happened in Papua New Guinea in 1998 ?
220 villagers living in coastal communities there were killed by a local tsunami generated from an underwater landslide triggered by an earthquake
What is an active volcano ?
Has erupted since the last glacial period or within the last 10,000 years
What is the case study for living with volcanoes ?
Japan
How many active volcanoes does Japan have ?
110
How much of Japan’s land mass is mountainous ?
70%
What is a lot of Japan’s folklore associated with ?
Volcanoes
Why is Japan tectonically active ?
Where 4 tectonic plates meet and widespread subduction gives rise to intense volcanic activity
How many volcanic ruptions has there been in Japan in the last 2000 years ?
1200
What is mount Ontake ?
Strato Volcano
200km west of Tokyo
on Japan’s largest island , Honshu
Rises to just over 3000m and its summit is often snow covered
What is the eruption history of Mount Ontake ?
Been dormant for many centuries until a sequence of eruptions between Oct 1979 and Apr 1980
Further eruptions (some small phreatic )followed in 1991 and 2007
When did Mount Ontake erupt ?
27 Sep 2014
11:52
Was there warning of Mount Ontake ?
Erupted violently without warning
Wasnt under any alerts
Some increase in earthquake activity had been observed
How many people died Mount Ontake ?
63
What happened to environment mount ontake ?
Ash fall
Pyroclastic flows
Volcanic Bombs
Lahars
What did the Japenes Prime Minitser do after Mount Ontake ?
Shinzo Abe
Ordered military to assisst with emergency rescue operations
what is the other case study for living with volcanoes ?
Indonesia
How many eruption in Indonesia ?
80 in historic times , underestimate
How many of Indonesia’s inhabitant live within 100km of a volcano which has erupted in last 10,000 years ?
3/4
What is Indonesia’s tectonic setting like ?
Widespread subduction along the entire 3000km length of Indonesian archipelago
How was Indonesia formed ?
Island arc formed by subduction of the Indo-Australian plate beneath the Eurasian plate.
Meanwhile, to the east of the chain of islands. the continental shelf of northern Australia is in collision with the Eurasian plate
The plate movements produce very high levels of seismicity and volcanicity
What was the explosion of Krakatau ?
1883
Also generated a big tsunami
North of Sumatra, Lake Toba fills the cladera caused by the super volcano
What is Mount Merapi ?
STrato volcano
reaches nearly 3000m
Highly active
Eruption events in 1994,1997,2001 and 2006
On each occasion, a dome developed in the crater, which eventually collapsed , producing pyroclastic flows
Force was 3-4 VEI
How was the environment affected in 2010 Merapi eruption ?
Pyroclastic flows extended 4km to the north, 11.5km to the west, 7km to east and 15km to south
Lava bombs were thrown 4km from summit in all direction
Eruption happened at start of rainy season , triggering lahards fed by ash from eruption and earlier eruptions
Ash fall forced closure of Yogyakarta airport for fortnight
Emissions of sulphur dioxide caused acid rain to fall over a large part of the region
How many people were killed in Merapi ?
367
how many injured merapu ?
277
How many people became refugees because of Merapi
?
410,000
How did Merapi affect farming ?
Livestock killed and ash fall and pyroclastic flows amounting to 130 million metres cubed of material destroyed crops and infrastructure such as buildings, power lines and bridges
What is the population of Indonesia ?
256 million
what is the population of Japan ?
127 million
Why do people live in Java, Indonesia ?
Volcanic soils and tropic climate allow as many as three crops of rive to be grown in a year
Why do the slopes of volcanoes attract settlement ?
Waethered laava produces fertile soils especially in wet tropical regions
Intensove farming therefore supports very high population densities
How much land does Japan’s agriculture sector use?
13 per cent of the countrys land area but does so very intensively
Where are most of Japan’s hot rock location ?
80% in national parks pr protected hot spring locations.
How much fo Indonesia’s electricity comes from geothermal ?
3%
How are minerals associated with volcanoes ?
Sulphur - used in industrial processes such as production of chemicals
Japan used to mine sulphur at Matsuo but production ceased in 1972
East Java, Indonesia, sulphur extracted directly from crater of Ijen volcano. Lat erupted in 1999 but mining takes place from an active vent. Miners cut lumps of solidified sulphur by hand from near the lake which occupies most of the crater.
Water has pH of 0.5 , similar to battery acid, and the area is frequently filled by poisonous clouds of hydrogen sulphides and sulphur dioxide
what is the first case study for living with earthquakes ?
Japan
How many earthquakes does Japan experience every day ?
400
Since 2000, how many magnitude 7 earthquakes have hit Japan ?
23
Causing 16,000 fatalities
What is the population of Tokyo ?
36 million
What was the Great East Japan Earthquake (Tohuku
)?
11 March 2011
9.0 MW magnitude
occured along boundary between the Pacific and North American PLates
epicentre was 70km offshore of northeast Honshu Island
What are some geophysical facts about tohoku earthquake ?
lasted 6 minutes
undersea megathrust earthquake
Honshu island moved 2.4m east
Earth shifted on its axis by 10-25cm 400km of coastlune dropped vertically by 0.6m
Sea bed rose by 7m and moved westwards 40-50m
Tsunamis reaching up to 40.5 metres triggered
Many aftershocks
Tsunami waves reached Antartica
How many people died in 2011 earthquake ?
16,000 lives
Injured 6000 people
Why was it difficult to dispose of dead bodies in 2011 earthquakes ?
Mass mortality
Destruction of crematoriums, morgues and the power infrastructure
How many children were affected by the 2011 Earthquake ?
100,000 - Save The Children
How many kids were orpahned in 2011 earthquake ?
2000 orphaned or lost one parent
What happened to one elementary school on the cost in 2011 earthquake
lost 74 of 108 students and 10 out of 13 staff
What was the cost of 2011 earthquake
between 200 billion dollars to five times that amount
How many buildings destoryed and damaged in 2011 earthquake
Japan’s National Police Agency -
45,700 buildings destroyed
143,300 damaged
230,000 vehicles destroyed or damaged
15 ports affected
How many people lost electricity 2011 earthquake
4.4 million households and thousands of businesses
Why did many people lose electricity 2011 earthquake
Immediate shutdown of 11 nucklear reactors
Fukushima Daiichi nuclear power plant - all 6 reactors were so severely damaged by tsunami that plant was decomissioned
Plant’s cooling systems were disabled by sea water flooding, which led to a meltdown of reactor cores and the release of radioactivity
30km evacuation zone established around plant, and soils in surrounding countryside were contaminated by radiation
What happened to transport 2011 earthquake
Rod bridges damaged or destroyed
Northeast train services were badly distrupted
23 train stations swept away
How much debris 2011 earthquake
25 million tonnes
What happened to Japan’s stock market ?2011 earthquake
It fell as the implications for businesses such as Sony, Toyota and Panasonic were realised
Their production was hit by lack fo electricity
Overseas operations affected , supplies of parts exported from Japan were interrupted
What popular movement occured because of the 2011 earthquake
Against nuclear power
Concerns over safety standards and regulation of the nuclear industry became political issue
After brief period of shut down, current plan it to re-commission a sig number of the currently mothballed nuclear plants
Executives of companies involved in Fukushima power plant resigned
What is the other case study for living with Earthquakes ?
Haiti
Where is Haiti located ?
Poorest Country in Americas
Western end of Hispanola, shared with Dominican Republic
Why is there Erathquakes in Haiti ?
Lateral movements typical of conservative margins whereby the Carribean plate is slipping eastwards relative to the North American plate
When did the Haiti Earthquake happen ?
12 Jan 2010
4:53 pm
What are the geophysical details about Haiti 2010 Earthquake ?
- 7.0 MW
- A slip along a 40km section of the Enriquillo fault
- Epicentre 25km southwest of Port-au-Prince
- Focus - 12km
Shaking lasted 12-14 seconds
What were the aftershocks of Haiti 2010 Earthquake ?
Within 20 mins of 6.0 MW and 5.7MW
Another of 5.9 MW on 20 Jan
Total of 51 aftershocks within a year
How many gov buildings were destoryed Haiti 2010 Earthquake ?
All but one of the 22 gov buildings in Port-au-Prince
How many deaths Haiti 2010 Earthquake ?
316,000 - but other estimates 46,000-84,000
How many buildings were destroyed Haiti 2010 Earthquake ?
Over 300,000 houses and 30,000 commercial buildings eaither damaged or destroyed
Displacing as many as 1.5 million people
What was the vulnerability of the population before the Haiti 2010 Earthquake ?
50% had no access to fresh water
Over 50% had no access to most basic health care
Literacy rates were among worst in world
How did Cholera spread after the Haiti 2010 Earthquake ?
Broke out in Oct 2010
First case was detected close to the UN base for Nepalese troops bought in to help with the reconstruction effort.
What was the cholera epidemic like after Haiti 2010 Earthquake ?
800,000 cases been recorded
Death toll - 10,000
Where is Haiti in the Un’s Human Development Index ?
2009 - 149th
2020- 169th
How many people are undernoruished in Haiti Haiti 2010 Earthquake ??
from 2009 and 2020, increased to 3.7 million
what is the population of Haiti ?
11.7 million
By 2018, how much aid had been spent in Haiti
?
11 billion US Dollars
How much money did Haiti have to pay the French government for the loss of enslaved people
In todays money, 21 billion us dollars
They did not pay it off till 1947
What is the Haitian economy made up of ?
Agriculture Rice was main crop
farms were small but often self-sufficient
What has the economy been like after Haiti 2010 Earthquake ?
Aid money has not, by and large, been directed at a economic recovery, with schemes such as the establishment of tourism and a more diverse economy less relaint on US companies that have not delivered very much
- The Haitian economy has hardly grown since the earthquake
Its largest income sources are remittances :money sent to the country by expatriate Haitians working abroad , providing 25% of its GDP, following by foreign aid, which provides 20% of its annual budget
What is the disaster risk equation ?
Risk = Frequency or magnitude of hazard x level of vulnerability / Capacity of population to cope and adapt
What factors does the scale of physical exposure to earthquake and volcanic hazards depend on ?
- frequency
- magnitude
- types of hazards generated by them in a particular locations
-number of people living in an earthquake prone or eruption prone area
What is vulnerability concerned with ?
The ability of a person or community to withstand exposure to snd risks from a hazard (earthquake/volcano)
What is resilience ?
An inidication of the rate of recovery from a hazadous event that has put an individual and/or community under stress
About how well a society are able to function at an accepatbe level when a disabling force has affected it.
What human activities have led to an increase in the frequency of natural disasters ?
Deforestation
leads directly to flloding
What are the physical factors which influence the response to a disaster ?
Speed of onset
Magnitude
How long it lasts
What are the human factors which influence the response of a disaster ?
Level of monitoring
Degrees of preparation
Quality of relief
Quantity of relief
What is a disaster response curve ?
What does the shape of a disaster response curve change in accordance with ?
According to different hazards
What can be done to ‘modify the event’ for tectonic hazrads ?
-Not possible for most volcanic
But, Lava dispersion channels
- spraying lava to cool it so it solidifies
slowing lava flows by dropping concrete block
For Earthquakes -
- Nothing can be done
What can be done to ‘modify people’s vulnerability’ for managing tectonic hazards ?
Education - Recognise signs of possible eruption , what to do when eruption occurs, e.g. evacuation routes , drills to practice
Community Preparedness - e.g. buildings of tsunami shelters and walls
Prediction and Warning - increasing use of technology to monitor active locations
Hazard-Resistant Building Design - e.g. cross bracing to support during quakes
Hazard- Mapping - Predicted lahar routes
Land-use zoning -
What can be done to ‘modify people’s loss’ when managing tectonic hazards ?
Emergency Aid -
Disaster Response Teams and equipment - helicopters
Search and rescue strategies
Insurance for buildings and businesses
Resources for rebuilding public services
What is better than a multi storey building ?
A stepped profile
Considerable stability against lateral forces
Why are multi storey buildings bad in earthquake prone areas ?
They can sway , especially towards their tops
s the site of building influence the building against earthquakes ?
Building near known faults or on soft soils such as alluvium increase the chance of damage and collapse
Steeper the slope angle , the more vulnerable it is to mass movement during an earthquake as the stresses on the slope may become so great that the slope fails
Why is a steel framed and cross-braced construction good ?
Including the basement
, help hold building together and absorb a lot of the energy when the building deforms during an earthquake
Why are deep foundations on soft soils good ?
Help prevent the effects of liquefaction
Why is the fitting of energy-absorbing pads good ?
In the foundations of the building
Absorb horizontal energy from an earthquake being transmitted
How does Indonesia’s Centre for Volcanology and Geological Hazard Mitigation monitor volcanoes ?
(CVGHM)
eST 1920
First seismograph was set up on Mount Merap i in 1924,
Gradually been able to upgrade the monitoring instruments and widen their geographical coverage
More than 60 volcanoes now ,onitored
Siphisticated equipment measures gas emissions, inflation as magma rises and earthquake activity in some, but not all of Indonesia’s Volcanoes
How do CVGHM work with local governments ?
Advise them on mitigation strategies such as community preparedness
How do Indonesia modify loss ?
Even though its a lower-middle income country it has well-trained and well-equppied emergency services and military Experieced in search and rescue
Temp shelters in safe zones are available
Authorities have cleared river channels of volcanic material to reduce flooding
What is Italy’s tectonic setting ?
Complicated by several fracture zones in the Mediterranean where the African and Eurasia plates meet
How does Italy modify the event of a volcano?
Slowing and diverting lava flows from Etna
Earth barriers , large concrete blocks dropped into the lava flow and channels dug to divert flowing lava away
What is the CFCRV ?
Volcano Risk Service
Italy ?
What do the CFCRV do ?
- long-term analysis of the eruption patterns of individual volcanoes
-international comparison with similar eruptions elsewhere - constant monitoring e.g. seismometers, tilt meters, analysis of gas emissions, aerial and satellite surveys
- a well established alert-level sequence understoo by emergency services, gov and communtiies
- closure of airports
What has been destoryed in Italy by Mount Etna ?
Houses
Farms
Livestock
Orange and lemon groves
Tourist Facilities
How have casualties been minimal at Mount Etna ?
Timely evacuations based on accurate data and well-trained public services such as fire, police and military
What was the monitoring system like in Haiti before the 2010 earthquake ?
No monitoring system
Who supported Haiti’s Earthquake awareness and monitoring after earthquake 2010 ?
USGS
Support from US Agency for International Development (USAID).
How many seismic stations are operating in Haiti ?
15
What are the faults with Haiti’s earthquake monitoring systems now ?
Not enough money to staff a 24hour team
How has progress been made with hazard mapping in Haiti ?
Showing areas especially at risk
Such as areas with softer sediments liable to liquefaction
What does Haiti not have whe modifying vulnerability ?
A national disaster risk management plan
What is the most pressing problem in Haiti for modyfying vulnerability ?
The inability of the state to enforce earthquake resistant building design
No gov approved building code
What is evidence of Haitis political instability ?
It has had 4 presidents and 7 prime ministers since 2010
How much did donors pledge to Haiti’s recovery ?
5.3 billion us dollars , to be spent over two years
Ho many US households donated to Haitian charities ?
45 %
How much money did the American Red Cross raise for Haiti ?
486,000,000 dollars
How many new houses were built by the American Red Cross in Haiti ?
6
How many houses did USAID plan to build compared to how many they actually built ?
15,000
Original estimate of that cost - 59 million dollars
Actually built - 900
Where is the most of the NGO money for Haiti ?
2/3 of the money raise remains in the bank accounts of the aid money managers that were there before the Earthquake
How does Japan research and monitor for earthquakes ?
Japan Meteorological Agency (JMA)
Responsible for providing information and warnings of impending earthquakes and tsunamis
Detailed disaster planning involves a wide range of organisations , e.g. govs, medical services, fire, military, transport, telecommunications companies
Whay are buildings with aseismic design in Japan for modifying vulnerability ?
Steel frames and braces capable of moving without collapsing, rubber shock absorbers in foundations, very deep foundations into solid rock
A soft storey at the bottom of tall buildings such as a car park, which collapses, allowing upper floors to sink down onto it
Counter weights on roofs, which move during earthquake
Suspension bridges capable of movement rather than rigid cantilever design
flexible joints in underground utility pipes
Wjat are the other things Japan does to modify vulnerability ?
- Fire proofing older wooden buildings, which are common in historic districts
- Land-use zoning that provides for open spaces where people can assemble after an earthquake
- Controlling building in locations susceptible to excessive ground shaking or liquefaction
-Tsunami warning systems off the coast - Refuge sites on permanent stand-by equppied with tents, bottled water , blankets
-Community preparedness - ongoign education and training
What are Japan doing to modify loss ?
Well-rehearsed recovery and reconstruction plans, at national, regional and local levels, can be actioned immediately following an earthquake
Aim is to rebuild physically, economically and socially as quickly as possible
