Conservative plate boundaries 3.1
Izmit, Anotolian strike-slip fault systems 3.12
Izmit is a bay in north west Turkey situated on the North Anotolian Fault Zone. This zone is the result of stress on the Anotolian micro plate which consists primarily of the the land mass Turkey. The plate is being squeezed and forced West at the rate of an inch per year by the surrounding African, Eurasian and Arabian plates which combine to create several conservative faults as all of the plates are moving west at different speeds, similar to California. Coastal areas in Turkey therefore become very hazardous as there is a high risk of earthquakes due to multiple Anotolian faults.
In 1999 one such earthquake struck in Izmit as the result of a shift in the strike-slip North Anotolian Fault Zone between the Anotolian plate and the Eurasian Plate which killed up to 45,000 people in non-official reports. The epicentre was 17km deep and created a quake measuring 7.6 on the richter scale. As a result of the shift a 150km rupture was also created traveling East from the quake's epicentre in a step like formation that measured up to 5m high. Overall the plate boundary has proved itself very dangerous but there are other factors involved in the creation of this hazard.
One example is the physical location of the earthquake and many other potential risk zones. As Anotolian faults run across the coast of Turkey there are risks of secondary hazards. In the 1999 Izmit quake the coastal rupture created a tsunami 3metres in height which hit the populated bay of Izmit, amplifying the hazard.
Furthermore coastal locations are also heavily populated as they are attractive for resources such as fishing and transportation. As shown in Deggs model the 1999 quake could not be a hazard without its proximity to populated towns such as Izmit and Istanbul which were both affected by the earthquake.
There are also geological factors to be considered. Unlike Loma Prieta this earthquake struck in north west Turkey, an area of soft rock formed mainly from sea soil. Therefore the land was less stable and more vulnerable to movement. As a result more buildings and infrastructure collapsed creating more of a hazard to life and the economy.
As shown in the case of the Izmit 1999 earthquake the plate boundary is important but other factors are also influencial .... [relate back to quaestion here in conclusion and throughout]
[Information found on geography.com and cross referenced with several academic blog pages. Information about types of plate boundaries found in geography A2 edexcel textbook]
Tuesday 22 January 2013
Monday 7 January 2013
Unit 4 Revision Hazards
Quick Case Study.
Sichuan Earthquake 2008
In 2008 an earthquake hit Sichuan province with an epicentre north of the city Chengdu. The magnitude of the quake measured 7.8 on the Richter scale and killed over 67,000 people. The epicentre of the quake was 19kms deep and lasted less than three minutes there were as many as 100 major aftershocks recorded over magnitude 5. As a result a rupture in the land formed along the fault stretching around 250kms in a north east direction from the epicentre and displaced the land in a step like split up to 9ms high. The quake was felt in several surrounding countries such as Russia and India but the area of destruction was mostly limmited to the Chinese province.
Sichuan province sits on a series of thrust faults created under immense pressure from the divergence of the Indian and Eurasion plate over the past 50m years. This has created folds (high relief) and cracks (mid-margin faults) in the crust. Even though the Longmen Shan fault was the cause of this 2008 earthquake, the rupture released such a lot of energy that it continued along the Fold and Thrust Belt (FTB) forming a two pronged rupture and destruction over a wider ariel extent. The reason why stress builds at this fault is because of the slowing of the Eurasian plate. The Eurasian plate is pressured into a north west direction but between the Sichuan basin and mountains the movement slows by 4mm per year.
The potential causes of the Sichuan earthquake as a hazard are:
Sichuan Earthquake 2008
In 2008 an earthquake hit Sichuan province with an epicentre north of the city Chengdu. The magnitude of the quake measured 7.8 on the Richter scale and killed over 67,000 people. The epicentre of the quake was 19kms deep and lasted less than three minutes there were as many as 100 major aftershocks recorded over magnitude 5. As a result a rupture in the land formed along the fault stretching around 250kms in a north east direction from the epicentre and displaced the land in a step like split up to 9ms high. The quake was felt in several surrounding countries such as Russia and India but the area of destruction was mostly limmited to the Chinese province.
Sichuan province sits on a series of thrust faults created under immense pressure from the divergence of the Indian and Eurasion plate over the past 50m years. This has created folds (high relief) and cracks (mid-margin faults) in the crust. Even though the Longmen Shan fault was the cause of this 2008 earthquake, the rupture released such a lot of energy that it continued along the Fold and Thrust Belt (FTB) forming a two pronged rupture and destruction over a wider ariel extent. The reason why stress builds at this fault is because of the slowing of the Eurasian plate. The Eurasian plate is pressured into a north west direction but between the Sichuan basin and mountains the movement slows by 4mm per year.
The potential causes of the Sichuan earthquake as a hazard are:
- Lack of sufficicient mapping/ building regulations
- Dense population of 15m with close proximity to hazard
- High magnitude earthquake over a wide ariel extent
- Low GDP only 25% of global average ($8,500) vulnerable
- High relief limits accesss and poses an additional risk of land slides
- Severe aftershocks an extension of the hazard
- Last significant quake over 70years ago, low perception of the risk
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