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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