The province's seismological base affiliated to the Geophysics Institute of Tehran University recorded the tremor at 16:58 local time (13:28 GMT) with its epicenter in an area 33/33 degrees in latitude and 38/30 degrees in longitude.
Earlier, a mild earthquake measuring 3.4 on the Richter scale hit the outskirts of Khorramabad in the morning.
Two other earthquakes jolted Khorramabad's suburbs on Thursday morning and afternoon each with a magnitude of 4.2 and 4.1 on the Richter scale, respectively.
There were no reports of possible casualty or damage caused by the three tremors.
Iran is situated on some of the world's most active seismic faultlines and quakes of varying magnitudes are usual occurrences.
... Payvand News - 1/15/05 ... --