Paper 1- Tectonic hazards Flashcards
where are volcanos found?
Wherever magma rises to the surface: conservative margins, subduction zones and hot spots
What three substances do volcanos emit
Lava, pyroclastic material, Gases
While magma is molten rock beneath the surface, lava is…
magma running over the surfcae
Acid lava characteristics
High silica content
temp around 700 degrees
very viscous, sticky
forms rhyolite or andesite rock
associated with destructive plate margins
Basic lava characteristics
Low silica content
Temp around 1200 degrees
non-viscous, runny
forms basalt rock
associated with tensional margins and hot spots
why are acid eruptions more dangerous?
Pockets of gas - when exploding its sticky
Example of a shield volcano
Mauna Hoa in Hawaii
Example of a composite cone (strato volcano
Mt Fuji
Mt Rainier
Lava flow primary impact
Eruption of Eldfell, at Haimaey, Iceland 1973
lava destroyed over 300 buildings.
But town and fishing port were saved by spraying water
Pyroclastic flow primary impact
E.g. Eruptionn of mt. Pelée, Martinique in 1902
A hot ash cloud wiped out St Pierre, over 25,000 deaths
Ash and ash fal primary impact
E.g. Eyjafallajokull, Iceland 2010
Glacier ice on top of the erupting volcano cause a huge ash cloud that caused over 100,000 flight cancelations and around 1bn dollars
Volcanic gases primary impact
E.g. Lake Nyos volcano, Cameroon in 1986
A large cloud of CO2 was released from the lake within the crater, this travelled downhill 15 miles, killing 1700 people
Volcanic mudflows (lahars) secondary impact
Eruption of Nevado del Ruiz, Colombia in 19985
Volcanic ash and rocks mixed with snow and ice on mountaintop to produce lahar
Swept across the town of Armero killing 23,000 people
Tsunamis secondary impact
E.g. Eruption of Krakatau, Indonesia in 1883
caused the collapse of the island producing large tsunamis that killed 36,000 people
VEI - Volcanic Explosive index
from 0 to 8
Each step up from 2 is a 10x increase in the volume of solid material produced by the eruption
E.g. 1km^3 Mt St Helens
Super volcano 10,000km^3
Earthquake definition
Sudden ground movements/ Earth tremors
Occurs, when crystal rock accumulates strain the suddenly moves or breaks along a fault
Energy is released in the form of Seismic waves
“focus” of an earthquake
The point within the crust where the earthquake rupture starts
Epicentre
The point on the ground directly above the focus
The Richter scale
Measures magnitude of earthquake
Determined using seismographs
Scale is logarithmic
Tectonic forces capable of generating earthquakes no stronger than al little over nine on the richter scale
Earthquakes low on R scale are more frequent
What is the Mercalli scale
Measures the devastation of an earthquake on a 12 point scale
A subjective assesment of damage done
Primary impacts of a strong earthquake
Fault scarps/ surface ruptures
collapsed buildings
damaged infrastructure
secondary impacts of an earthquake
fire
landslides
tsunamis
Liquefaction - makes water more liquid than solid
Disease and famine
What is meant by primary and secondary effects of tectonic events?
Primary refers to direct effects on people + infrastructure
e.g. casualties and building damage
Secondary effects are triggered by the initial event
e.g lanslides due to slopes made unstable
+ Economic factors
Immediate and long term responses to tectonic events meaning
Immediate refers to rapid emergency response
Long term = delayed and long duration responses
e.g. Government stratergies to rebuild
Why do HICs fare better than LICs countries in disasters
HICs have more awareness
HICs have better methods of mapping and monitoring the hazards
Often corruption in LICS
HICs have more money to spend on emergency services
E.g. Mount St. Helens USA 1998 careful monitoring and evacuation resulted in less causualties (57 deaths)
E.g Nevado del Ruiz, Colombia (1985) lack of careful monitoring lead to 23,00 casualties
Haiti background information earhtquake
Took place on 13th Jan 2010
Struck a local time of 16:50
Magnitude was 7.0 on richter scale
Haiti lies between Caribbean + North American plate
Arose at a fault which runs through Haiti
Christchurch NZ background information earthquake
Suffered from its previous earthquake that year
Situated in South Island
Home to around 400,000 people
Hit on 22nd Feb 2011
6.3 on the Richter scale
Epicentre was around 6km from Christchurch
Primary Haiti impacts
Primary: 230,000 people died,
300,000 injured,
1 million left homeless,
250,000 residential buildings + 30,000 commercial buildings were destroyed, their buildings were made cheaply, could be due to corruption
Secondary Hait impacts
Secondary: impact on industry,
main production was clothing. 17th largest supplier of clothing products sold to USA in 2008,
left economy poorer and prices raised due to demand, tourism effected
e.g Cruise ships, airlines and hotels were in demand - quake destroyed this
Farming 5 - 6 million lived in rural areas 85% of those people framed
accounts for 26% of Haiti’s economic output
ruined crops, cattle + roads - slowed operation down
before the earthquake priorities were focused on feeding pop.
Christchurch primary impacts
loss of buildings
old city centre was destroyed
this cost round 10$ billion to redevelop the city
the other $10 billion was for other areas
185 people killed
6000 injured
Christchurch secondary impacts
Landslides
glacial falling into the seas
Rugby world cup had to be moved- effecting the local economy
Haiti responses
Rescue those trapped in rubble
Main hospital was destroyed
Health needs were addressed by 6 international + 8 haitian medical teams
People desperately needed basics
UK disaster comittee donated £23 million
US sent aid by sending planes full of rescue workers and ships with thousands of soldiers
Long term respones = charities–> infrastructure + medical resources
Christchurch response
needs of the local people
Plans to demolish the old city centre core
Long term responses came two years late: Job creation, innovation, well being for the locals
other support was fundraised (8.8 billion dollars)
Provided sewage, road and transport needs
Some say good came from it = oppertunity to redevelop
Planned stratergies fro Christchurch
1 = government to redevelop the town (20 billion $) e.g. economic growth, leadership, awareness
2=”Christchurch central development plan”
Aim was for a new central core, significant points to show strength of city, local people got involved, brought community closer
