case studies hazards Flashcards
volcanoes - japans tectonic setting
four tectonic plates meet and widespread subduction gives rise to intense volcanic activity
1200 volcanic eruption in the past 2000 years
mount ontake - features
strato volcano on honshu - 200km away from tokyo
dormant until 1980 then eruption in 1991 and 2007, then 2014
area was popular with climbers and trekkers - noted as a tourist destination - facilities including lodhe near summit
mount ontake eruption 2014
erupted killing 63 people (mostly climbers) and large areas surrounding the volcano were affected by ash fall, pyroclastic flows, volcanic bombs and lahars
not under any alerts or warnings - although some increase in volcanic activity had been observed
aftermath of mount ontake erruption
japanese PM ordered the military to assist with emergency rescue operations
for a while, air space in the vicinity of the eruption was closed as a precaution against the possible damaging effects of fine volcanic ash on aircraft engines
indonesia - volcano - indonesias tectonic setting
much of indonesia is an island formed by subduction of the indo - austalian plate beneath the eurasian plate
to the east of the chain of islands, the continental shelf of northern australia is in collision with the eurasian plate
large numbers of volcanoes are highly explosive eg Krakatau eruption 1883 also generated a tsunami
features of merapo
strato volcano
highly active - eruption events - 1994,1997,2001,2006,2010
merapi eruption 2010
367 deaths, 277 injured, 410,000 in volcanic vicinity became refugees
vei - 4
dome developed in crater, which eventually collapsed, producing pyroclastic flows
lava bombs thrown 4km from summit in all directions
eruption at start of rainy season - triggering lahars
ash falls forced the closure of yogyakarta airport for over a fortnight and emissions of sulphur dioxide caused acid rain to fall over large part of region
large numbers of livestock killed
ash fall and pyroclastic flows amount to 130 million m squared of destroyed crops and infrastructure
japans tectonic setting - earthquakes
movements along plate boudaries lying just offshore of the japanese mainland created a risk of tsunamis
pacific coastal zone - densely populated - tokyo (36 million), osaka (19 million)
the great east japan earthquake 2011 - tohoku
9.0 mw
epicentre - 70km east of oshika penninsula
Very large tsunamis triggered, reaching heights of up to 40.5m in places when hitting the coast
There were many aftershocks, some of which of 7.0mw -8.0 mw in strength
Social impacts of tonoku earthquake
16,000 killed, 6000 injured - 70-90% by drowning
Mass mortalities and destruction of crematoriums meant authorities felt they had no choice but to bury bodies in mass graves as quickly as possible to reduce the chance of diseases bein spread
Children separated by families - save the children reported that 100,000 children were affected - most children were at school when earthquake struck
2000 children either orphaned or with one parent
Destruction of infrastructure for example housing schools and health centres was on such a scale that reconstruction was still taking place five years later
Economic impacts
£181 billion
45700 buildings destroyed
10% of fishing ports damaged
4.4 million households without electricity due to immediate shutdown of 11 nuclear reactors
Fukushima power plant - plants cooling systems were disabled by sea water flooding which led to a meltdown of reactor cores and the release of radioactivity - contaminating soils and sea - still today affecting fishing industry
Transport infrastructure- many road bridges were damaged or destroyed and in the northeast train services were badly disrupted - 23 train stations swept away
Overseas operations also affected as supplies of parts exported from japan were interrupted
Political impacts of tohoku
Japanese govt injected billions of yen into the economy to bring stability- this increased government debt at a time when its reduction was a prime political aim
Popular movement against industry became a political issue
Spread around the world eg anti nuclear lobby in Germany used the incident to support their arguments nuclear power
Nepal’s tectonic setting - earthquakes
Situated in the middle of the collision where the indo-Australian plate meets the Eurasian plate - all these plates grind against each other, pressure build up and the energy is released as earthquakes
Pre - historic lakes filled many of the valleys and then legacy is hundreds of metres of relatively soft sediment
As seismic waves pass through this material they are amplified causing structures to swing violently. Depending on the water content of the soil at the time of the quake m, liquefaction can be a major hazards
Gorkha earthquake
April 2015
7.8 mw
A slip along the main frontal thrust fault in the collision zone
51 aftershocks including a 7.3 mw in may 2015
Many landslides
Snow and ice avalanches including on Everest
Social impacts of gorkha earthquake
8800 deaths 22000 injured
Avalanches on Everest killed 20
More than 2.8 million people were displaced from Kathmandu- many migrants in the first place
473,000 homes destroyed
1 million required food assistance
Due to quake an increase in trafficking women and girls from the poorest families who weee homeless to south Asian brothels
Most aid controlled by men - discriminate against women
