A magnitude 4.6 earthquake on the Richter scale hit outside the town of Faryab in the province of Kerman, south-east of Iran.     A statement by the earthquake centre of the Institute for Geophysics at the University of Tehran, carried by Iranian Al-Alam sattelite channel said the earthquake occurred today and didn\'\'t cause any casualties or damage. Iran is located on seismic fault lines and is prone to earthquakes, experiencing at least one slight quake a day on average.