A powerful earthquake struck eastern Turkey this Sunday near the city of Van with an estimated population of 370,000.
Turkey’s Kandilli Observatory issued a preliminary magnitude of 6.6. However, the United States Geological Survey has issued a preliminary moment magnitude estimate of 7.2 and a focal depth of 20 km. If the USGS estimate is closer to the actual magnitude, it is the largest earthquake to strike Turkey since the 1999 magnitude 7.2 Duzce earthquake, which killed close to 1,000 people. Earlier that year, a magnitude 7.6 near Izmit in northwest Turkey killed nearly 20,000 people.
According to city officials, today’s earthquake has collapsed buildings in Van and the nearby town of Ercis, although the numbers being reported are conflicting. The Turkish Red Crescent said that 10 buildings collapsed in Van; other reports put the number in Van and nearby towns at 45. A number of aftershocks have followed the mainshock, two of which were magnitude 5.6.
According to AIR, in Turkey, the majority of residential and commercial buildings located in urban areas are reinforced concrete (RC) with masonry infill. Most of these buildings, which are three to seven stories high, have cast-in-place RC frames with hollow brick infill panels and partition walls that are not connected to the frame. Research regarding the poor seismic performance of RC buildings during historical earthquakes in Turkey reveals design and construction deficiencies, including a lack of lateral resistance in the framing systems, irregularities in strength, poor quality construction materials, and inadequate reinforcement detailing and confinement in beam-column joints.
It is in the very early aftermath of this event, and source parameters may change as reports continue to come in from seismic networks around the world. Further information will be provided Monday, October 24th as more detailed data is available.
Source : AIR Worldwide Press Release