Heightened odds of large earthquakes near Istanbul: An interaction-based probability calculation

We calculate the probability of strong shaking in Istanbul, an urban center of 10 million people, from the description of earthquakes on the North Ana tolian fault system in the Marmara Sea during the past 500 years and test t he resulting catalog against the frequency of damage in Istanbul during the preceding millennium. Departing from current practice, we include the time -dependent effect of stress transferred by the 1999 moment magnitude M = 7. 4 Izmit earthquake to faults nearer to Istanbul. We find a 62 +/- 15% proba bility (one standard deviation) of strong shaking during the next 30 years and 32 +/- 12% during the next decade.