tectonics Flashcards
(10 cards)
Mount Nyiragongo
-location
-cause
-impacts
-response
-what made it worse
Congo, May 2021.
Cause- divergent plate boundary where the African plate is being pulled apart into the Nubian plate (east) and Somali plate (west), causing lava to rise between. COMPOSITE
Impact- 32 deaths, due to asphyixation cos of toxic gases traffic accidents during evacuation, was also a prison break. 54o children seperated, 1700 homes destroyed, 17 villages wrecked. Infromal sectors like markets destroyed, no income. WORSE DUE TO RURAL ISOLATION DUE TO EXCLUSION ZONES, 73% IN POVERTY
Response- predisaster: evacuation plan prepared due to 2002 evacuation, not executed well as traffic accidents occurred, led by government services BAD AS LIC, NO INVESTMENT IN GOVERNMENT SERVICES+CORRUPTION , 40,000 evacuated BUT ebola, covid and poverty all made evacuation more difficiult. Warning 2 weeks in advance however crticised not early enough.
Post disaster-humanitarian aid sent by rwana drc for a year. (bottom up approach) Aid from the UN but stopped due to corruption, leaving people without internet. (misused as aid)
Response can be classed as good due to improvement from 2002.
Fagradalsfjall
March 2021, iceland
divergent between eurasian and north american causes magma to rise SHIELD VOLCANO
impacts- 0 deaths 0 casualties, LOW POP DENSITY
3-5m barriers for volcano were overtopped by lava, in place to protect telecomms and roads
response-
predisaster- ash cloud monitering, scientists worked to track volcanic activity
immediate-local evacuations and relocations due to risk of exposure to volcanic smog and co
alert lowered from orange to yellow
post- building back of better protection that wont be destroyed, EASIER DUE TO HIC AND GOOD GOVERNMENT
la palma
cumbre vieja volcano
september 2021
on a intraplate, occurrede on hot stop. Volcanic rdige on south of island. BASALTIC, SHIELD VOLCANO LESS DANGEROUS THAN A COMPOSITE AND BASALTIC LAVA IS LESS DANGEROUS DUE TO LESS VISOCITY SO RUNNY AND THIN SO GASES CAN ESCAPE ISB SAFER THAN RHYOLITIC LAVA IN SUPERVOLCANO LIKE YELLOWSTONE
implementing a multi-faceted approach that included monitoring magma buildup, issuing warnings, and evacuating residents. evacuated 7000 ppl
no deaths, 2500 buildings destroyed, 66km of roads blocked or destroyed.
ash cloud meant closure of air space, ashfall affect banan production. Damage exceed 900 million
response- temp accom for 7000 evacuated, governemnt used compilasary purchase measures for those who’s homes were destroyed GOVERNMENT HAD MEASURES IN PLACE- GOOD PREPAREDNESS
emergency subsidies granted and 70 million to support local industry like farming etc.
IN 20TH CENTRUY POP GROWTH OF 450%
VOLCANO TOURISM 146 thousand per year
decline of 50% in tourism after eruption
Assess the relative importance of physical factors and processes in explaining the impacts of volcanic eruptions.
p1- La Palma, sep 2021
type of lava and shape
basaltic and shield
thin, runny lava, gases can espcae low visscositiy
Less dangerous, explanins why 0 casualties and deaths
however if it was yellow stone supervolcano with rhyolotic lava would alter global climate for years and kill all in its path
p2- Mt Nyiragongo, DRC, May 2021
strong prevailing wind plays role
strong wind means travelling of ash cloud
severe impacts of 32 deaths due to asphyxiation of toxic gases,
howver human impacts- low level of development
indirect deaths due to traffic evacuations difficult
rural isolation- exclusion zones- fertile land, subsitence farmers, due to 73% in poverty,
poor government services not upholding exclsuion zones due to lic, not advanced enough etc, caused indirect deaths.
p3- Fagradalsfjall March 2021 in Iceland,
divergent- Eurasian and North American but 0 deaths casualties, howver Mt Nyiragongo is divergent involving Africsn and Nubian but had 32 deaths,
however big diff in pop density
32 deaths in DRC due to higher pop density, more people at risk, almost 750,000 near contrast compared to wherehas rejykanes near the volcano is only 30,000.
conclusion- conclusively, physical are more important, can have global impacts such as Krakatoa which cooled world globally by 0.6, highlighting lack of significance level of development or good governance have when an explosion is so large. Human factors can worsen a tectonic hazard significantly but physical factor plays leading role.
assess for human factors in volcanic eruptions
p1- Mt Nyiragongo in DRC in May 2021
73% of people in poverty, focused in primary indsutry, many subsiteicne famrers
exclusion zones not upheld due to volcano areas having fertile land, improving yield.
poor governemnts services due not enough investmnet, training etc, means they are not upheld.
made evacuation more difficult causing many indirect deaths such as traffic incidents due to evacuations.
p2- Fagradalsfjall, Iceland, March 2021
low pop density, 30,000 in rejkanes area so 0 deahts/ casualties, evacuations only occurred as a precaution contrast to Mt Nyiragongo population of 750,000 including city of goma. More people there to get injured/ die.
p3- PHYSICAL
La palma, basaltic lava which is runny, thin, less viscosity, so had 0 deahts, BUT rhyolotic lava, occurs at supervolcanos such as yellow stone would have global impacts such as cooling globally of 6 degrees for years, and would kill anyone in its path, estimated to kill 90,000 people regardless of LIC or HIC.
conclusion-conclusively, physical are more important, can have global impacts such as Krakatoa which cooled world globally by 0.6, highlighting lack of significance level of development or good governance have when an explosion is so large. Human factors can worsen a tectonic hazard significantly but physical factor plays leading role.
paleomagnetism
gives evidence for tectonic theory and seafloor spreading
shows there are stripes in rock layer, and direction of stripe indicates magnetic field to pole
shows previous eruptions under water
and helps to reconstruct past plate movements like superconintent e.g. Pangea
but
is a complex process so may have some inaccuracies
so cannot fully rely on it ti predict location and timing of future events\
plate tectonic theory
began with Wegners theory of continental drift where he proposed continents move like rafts
developed to tectonic theory and evidence to support it:
mantle convections-
mantle is semi solid rock between crust
heat from core allows the less dense material to rise
as the material rises, it becomes cooler and denser so sinks again
causing convection currents that drive plate movement
this leads to ridge push and slab pull
1) ridge push is when there is gravitational sliding as plates move away from ridges, as plates move away from divergent plate boundaries, hot magma rises.
2) slab pull- new oceanic crust formed as mantle rises through cracks at divergent boundaries as slab pull moves older crust outwards, therefore creating a new sea floor.
seafloor spreading is measured by paleomagnetism
- confirms seafloor spreading, stripes in rock and layer and direction of stripe indicates the magnetic field towards the pole
it shows previous eruptions under water and helps reconstruct past plate movements like the supercontinent of Pangea.
haiti earthquake
2010
desutective plate boundary, North American and Caribbean plates
occurred at Enquillo fault which moves 8cm per year so relaeases lots of energy
7.1 magnitude
human factors- one of poorest in the world, poorest in latin america, high rates of iniqualties
responses
immediate- manually lifting of rubble due to no lifting gear, “hope for haiti” raised 35 million, World food programme a appeal for 14 milllion ration packs thay would feed 2 million for 1 month
after 2 week- unprepared damage management due to poor gov, conflict and poverty, after 2 week only 25% of homeless had tents. World bank announced they would be suspending debts and would be in process of cancelling them
post disaster- world summit for haiti which proposed obligations to improve the political stability, stricter builder codes and find homes for displaced
impacts- 225,000 died mainly due to collapsed buildings
75,000 mass buried to prevent spread of disease
italian earthquake 2016
destructive 6.2 magnitude
3:36am so everyone asleep more danger
HIC, literacy rates are 99.5%
African plate converging and syndicating under eurasian plate, supports seismic gap theory
impacts- 298 died mainly 70% because buildings not adequate for seismic standards POOR GOV
4000 houses destroyed
rural isolation made it worse
pre disaster- early warning systems were unaffective due to short distance between epicentre and settlements
immediate- sniffer dogs, bulldozers and pppl attempted rescuing, 12 helicopters used as no raids, emergency funding of 50 million authorised by gov
post- preparedness plan called casa italia, prepare for long term not just emergencies, e.g seismic standards on buildings and 4 billion spent on strnegthinf schools
BUT
7 years on and many still in temp housing
l
Japan earthquake and tsunami 2011
destructive plate, Eurasian subductee by pacific, friction building up over time caused a mega thrust earthquake
9.0 magnitude
HIC, 99% literacy
15.8k died, economic cost of 235 billion
issues intensified due to secondary impact of earthquake which reached up to 40m high and decasted coastal areas, adding to death count
worsened due to rural isolation
immediate response- issued tsunami warnings 3 min after earthquake
declared 20km evacuation zone around Fukushima nuclear power plant to reduce threat of radiation
rescue teams from Us military, India, China , South Korea
long term- Reconstruction Policy council to develop tsunami resilient communities with 23 trillion budget, coastal protection policy enforced
