A moderate earthquake rocked Turkey's largest city Istanbul on Wednesday, but it was not immediately clear if there were any deaths or injuries. "A medium-sized earthquake measuring 4.5 (on the Richter scale) felt mainly in the Asian part of the city occurred. The epicentre was in the Sea of Maramara," a seismologist at Istanbul's Kandilli Observatory said. Witnesses noted that they felt the earthquake on both both the European and Asian sides of Istanbul. Although the Richter scale has no upper limit, values are typically between 1 and 9, and each increase of 1 represents a 32-fold increase in the amount of energy released. Typically quakes measuring up to 3 are not felt, while those between 3 and 4 are felt but do little or no damage. Strength 5 quakes are felt over a wide area with damage near the epicentre, while from 6 upwards the damage gets worse and the area wider. A massive earthquake rocked northwestern Turkey, including Istanbul, in 1999 killing more than 18,000 people and leveling large swathes of the industrialised region. Small earthquakes are a near daily experience in Turkey which is crisscrossed with a series of faultlines.
