Update: According to a press release from Bogazici University, intensities reached VIII. They also claim a depth of 5 km only. 138 people died, 350 were wounded and 970 buildings collapsed.
An earthquake with a magnitude of Mw 7.2 (EMSC: Mw 7.3) occured in Eastern Tureky in a depth of 10 – 20 km. The epicentre was situated close to the city of Van. More than 30 houses collapsed according to first reports. Despite only several dozens of people have been confirmed dead until now, the earthquake could have caused hundreds of fatalities. Surprisingly, the quake did neither happen at the North Anatolian Fault Zone nor at the East Anatolian Fault Zone. Those two strike slip systems are considered as the most dangerous faults in Turkey. The Van area lies in a broad zone of convergent movement of the Arabian plate vs. Eurasia, and mapped faults are in concordance with the oblique thrust mechanism observed at the 23 October 2011 event. Convergence rate is in the order of 25 mm/a there.
Moment tensor solutions (source: EMSC)
The seismic hazard map also shows Van and its surroundings being situated in avery dangerous zone:
Seismic Hazard in Eastern Turkey (source: USGS)
Now, this area suffered (instrumental) intensities of up to IX-X:
Instrumental intensities (Source: USGS)
The city of Van seems to have suffered widespread devastation, according to first news reports.
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Since many buildings in that poor part of Turkey are not constructed with proper aseismic measures, an event like this is capable of widespread devastations (however, a shallow 7.2 event would devastate most cities in the world…). USGS reports peak ground accelerations (PGA) of almost 0.5 g (4.1 m/s²) and peak ground velocities of 90 cm/s. Given the magnitude and the shallow depth, widespread earthquake environmental effects (EEE) like liquefaction, mass movements and secondary ruptures are likely. There might also be some primary ruptures, since several centimetres to more than one meter of vertical offset can be expected.
Geoblogosphere on the Turkey EQ:
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