Iran's southeastern province of Kerman has been hit by at least two strong quakes in recent days, injuring at least 18 people and damaging around 20 buildings, state media reported.
The first quake of magnitude 5.9 struck on early on December 12 about 56 kilometers north of Kerman, a city with a population of more than 820,000.
The tremor, initially reported as magnitude 6.2 by the U.S. Geological Survey before it was revised downward, was followed by dozens of smaller aftershocks.
During the night, early on December 13, a stronger quake of magnitude 6.0 struck the same area, the survey said. It was more shallow, only 10 kilometers deep, a factor that amplifies the shaking, the survey said.
The latest quake was centered 64 kilometers north of Kerman, it said.
"Overall, the population in this region resides in structures that are extremely vulnerable to earthquake shaking, though some resistant structures exist," the service said.
There were no immediate reports of damage, injuries, or fatalities.
State media reported earlier that no deaths were caused by the first earthquake, but at least 18 people were injured.
Pictures posted on state media showed people standing in streets in the quake zone to avoid being trapped by collapsing buildings. The 20 buildings reported damaged were mostly older structures, state media reported. The pictures showed collapsed mud-brick walls.
On December 11, another quake, which Iranian state media reported at 6.0 and the USGS reported at 5.4, hit western Iran, in the same region where a magnitude-7.3 earthquake killed at least 530 people last month.
There have been no reports of deaths or injuries from that quake.