This part 2 of our Myanmar March 24, 2011 reporting.Â Click here for Part 1, giving the full story from when the earthquake was reported.
UPDATE 27/03 – 01:13 UTC : Teraphan Ornthammarath, Ph.D. and Seismic Risk Evaluation and Mitigation Scientist working at the Regional Integrated Multi Hazard Early Warning for Africa and Asia is describing the origin of the earthquake as follows :
TheÂ fault that originated this earthquake is the Nam Ma fault originating from Laos to Myanmar.
It was described in Lacassin et al. (1998) that this fault marked the fossil of fault offset in Mekong river (20.80N, 100.45E).
There was no big earthquake since 1912 from this fault.
Below a number of very good graphics from the Chinese Earthquake Authority.
They are showing very well the extension of the shaking, the faulting zones and the kind of earthquake it was.
The map below shows the area of shaking. Dark red means a destructive or violent shaking.
The dark orange color is a severe shaking (MMI VIII)
The greenÂ means a moderate shaking.
Please note the the the extend of damage is not only related to the Magnitude. The composition on the geologic layers is also very important. A proof of this, is that the yellow and green colors in Thailand are relatively undamaged. The weak green shaking at the Chinese part of the border was however very damaging with more thanÂ 5,000 houses damaged.
The picture below gives a very good overview of the mapped Fault lines in the area. The epicenter of the 7.2 earthquake from March 24 is indicated with the blue star, just next to the fault line.Â The green bullets are cities (greater size = bigger city).
The white part of the map is Chinese territory. The purple fault lines going from the North-West to the South-East in China are responsible for the Yunnan earthquakes from January 2, 2011 (major damage) andÂ the Yunnan deadly earthquake from March 10, 2011 (killing 25 people and making (again) major damage).
Conclusion : The total area is very unstable at the moment.
The picture below shows the kind of earthquake it was. Apparently this was a strike-Slip fault.
Strike-slip fault = A fault whose relative displacement is purely horizontal.
Strike-Slip faulting is always very dangerous, even at some lower magnitudes.