My OperaAnatolian Tectonic Block
Tuesday, March 9, 2010 3:53:47 PM
A few days ago Turkey was struck by a strong earthquake at the East Anatolian fault. As you could see on the USGS tectonic map that I showed in my post on that occasion, the Anatolian block is bounded on the southeast by the East Anatolian fault and the north by the North Anatolian fault. The Anatolian block is moving west relative to the advancing Arabian plate at a rate of about 24 millimeters a year.
The North Anatolian Fault has often been in the news because of earthquakes. It is a 1,500-kilometer-long east-west trending fault that runs across most of Turkey. Since 1939, a progression of deadly earthquakes has been marching westward across the fault - westward towards Istanbul where there is now a seismic gap. A seismic gap is a segment of an active fault that has not slipped in an unusually long time when compared with other segments along the same structure, and people surviving the disastrous earthquake in Chile on Saturday 27 February 2010 will know what that means. In Turkey Istanbul is the next likely target. A new study, however, suggests Turkey’s largest city may be struck by a series of moderate earthquakes, rather than one big event.
Slip rates for the North Anatolian Fault have previously been reported as anywhere between 12 and 28 millimeters per year. Only the main branch of the North Anatolian Fault were so far taken into account. The new study included many of the smaller fault strands that have only recently been mapped. The new models, published in Nature Geoscience, indicate that the smaller faults are actually accommodating much of the fault’s movement. The North Anatolian Fault is therefore only slipping by between 12 and 17 millimeters per year - according to Hergert & Heidbach.
Even a moderate event of a magnitude of 7.0 could, however, do serious damage to Istanbul, a populous city with many high rises and somewhat lax building codes. Whether Istanbul is struck by a magnitude 7 or 7.6, the damage is likely to be substantial.
The North Anatolian Fault has often been in the news because of earthquakes. It is a 1,500-kilometer-long east-west trending fault that runs across most of Turkey. Since 1939, a progression of deadly earthquakes has been marching westward across the fault - westward towards Istanbul where there is now a seismic gap. A seismic gap is a segment of an active fault that has not slipped in an unusually long time when compared with other segments along the same structure, and people surviving the disastrous earthquake in Chile on Saturday 27 February 2010 will know what that means. In Turkey Istanbul is the next likely target. A new study, however, suggests Turkey’s largest city may be struck by a series of moderate earthquakes, rather than one big event.
Slip rates for the North Anatolian Fault have previously been reported as anywhere between 12 and 28 millimeters per year. Only the main branch of the North Anatolian Fault were so far taken into account. The new study included many of the smaller fault strands that have only recently been mapped. The new models, published in Nature Geoscience, indicate that the smaller faults are actually accommodating much of the fault’s movement. The North Anatolian Fault is therefore only slipping by between 12 and 17 millimeters per year - according to Hergert & Heidbach.
Even a moderate event of a magnitude of 7.0 could, however, do serious damage to Istanbul, a populous city with many high rises and somewhat lax building codes. Whether Istanbul is struck by a magnitude 7 or 7.6, the damage is likely to be substantial.
- http://www.earthmagazine.org/earth/article/321-7da-3-8
- http://www.nature.com/ngeo/journal/v3/n2/full/ngeo739.html
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