There were no immediate reports of casualties and the extent of the damages inflicted on the quake-hit area.
Since Thursday morning, nine quakes have shaken Iran's western regions near the common border with Iraq, including four measuring lower than 4 on the Richter scale.
"It's ongoing activity there", Randy Baldwin, a geophysicist with the USGS told The Associated Press.
Also, according to the USGS, the earthquakes hit at a depth of about six miles. Scientists consider earthquakes of magnitude 5 as moderate.
At least 530 people were killed, and injured people were about 7,500.
Last year, a 7.3-magnitude quake hit villages and towns in Kermanshah province, killing 620 people and injuring thousands of others. The last deadly quake was in 2003, where a 6.6 magnitude natural disaster killed 26,000 people in the city of Bam. Many people are still living in temporary homes and tents. No injuries or damage were reported.
Iran is located on major seismic faults and experiences nearly a quake per day on average.
In 2003, a magnitude 6.6 quake in the province of Kerman flattened the historic city of Bam, killing more than 26,000 people.
The official IRNA news agency says the temblor rocked the village of Hojedk, located about 700 kilometers, or 400 miles, south of Tehran early on Thursday.