Twenty years after a deadly earthquake, Istanbul "not ready" for the "Big One" Twenty years after a devastating earthquake ravaged the northwest of Turkey, Istanbulites live with the knowledge that another "Big One" is unavoidable, and that their city of 16 million is not prepared. On Saturday, Turkey will mark the anniversary of the 7.4-magnitude quake that hit Izmit -- around 100 kilometres east of Istanbul -- on August 17, 1999, leaving at least 17,400 people dead, including 1,000 within the economic capital of the country.