Several days ago Chris in Suburbia asked about the seismic hazard in the Istanbul
region of Turkey. I thought, given the inclusion of the Istanbul area as a site of far-field
triggering from Hindu Kush, that this would be a good time to summarize some of
the previous earthquake hazard and potential in the area.
The region of Istanbul and the Marmara Sea has experienced
43 event of Ms>=7 since AD 1. The number of destructive or
damaging earthquakes in the same period is about 650. Turkey
has been hit by more than 40 destructive earthquakes during
the 1900's alone (see Ambraseys ref. below)

Earthquakes in the Istanbul area often follow earthquakes in the
Izmit region of Turkey (and vice versa) about 2-3 years later. Examples
include:

358, 359 A.D - A catastrophic earthquake in the region of Izmit
nearly destroyed that city.

--> Feb 1, 363 - An earthquake does damage in Istanbul

542 Aug 16 - A severe earthquake east of Istanbul caused severe
damage ang loss of life. (M 6.4)

--> Sept 6, 543 - An earthquake west of Istanbul destroyed half
the city of Erdek and was severe at Istanbul (M 7.0).

554 Aug 16 - A destructive earthquake caused the collapse of
the better part of Izmit. (Ms 7.5)

--> Dec 14, 557 - A destructive shock hit Istanbul where many
homes were destroyed and people killed (Ms 6+)

1754 Sep. 2 - A great earthquake in the Gulf of Ismit which killed
as many as 2000 and destroyed everything.

--> Jan 20, 1757 An event of Ml 5.5 is felt in Istanbul

1855 Feb 28 - A destructive earthquake destroyed the city of
Bursa killing up to 5000. (M 7.5)

--> Sept 17, 1857 - A damaging earthquake hits Bursa and Istanbul

1877 Oct 13, - A damaging earthquake hits in the Sea of Marmara

--> Apr. 19, 1878 - A strong earthquake hits Istanbul

1894 Jul 10, A destructive earthquake in the Gulf of Izmit caused
extensive damage killing several thousand and destroying most
villages.

--> Sept. 14, 1896 - A local earthquake did much damage in Istanbul
--> Dec 1897 - Earthquake of Mw 6.4 near Istanbul

1963 Sep 18, A destructive earthquake hits near Izmit (Ms 6.4)

--> Oct 6, 1964 - A Mw 7.0 occurs just south of Istanbul.

1999 Aug 17 - A destructive earthquake hits Izmit killing at least
15,000.

-->

In general the movement of the force from the Izmit region
to subsequent earthquakes in the Istanbul area appears to progress
at about 0.2 km/day with a time between subsequent earthquakes
of 1-3 years.

Most of the details above come from the paper:

"Long-term seismicity of Istanbul and of the Marmara Sea region"
by N.N.Abraseys and C.F. Finkel, in Terra Nova, 3, 527-539.

Since it has now been 2.6 years since the Izmit earthquake,
Istanbul does appear to be in some immediate danger.

The far-field aftershock forecast from Hindu Kush also
cites Istanbul as being 34 - 36 degrees from the Mw 7.2
today, a distance at which far-field seismic triggering is
often observed.