(Adds 5.1 magnitude quake in southeast)
DUBAI, Dec 27 (Reuters) - One person died of a heart attack and at least 56 people were slightly hurt when an earthquake of 4.2 magnitude shook an area 50 km (31 miles) west of the Iranian capital Tehran on Wednesday, the state news agency IRNA reported.
Later on Wednesday, a quake with a magnitude of 5.1 hit the town of Hojedk in southeastern Kerman province, state television reported, adding that there were no immediate reports of casualties or damage.
On Dec. 12, an earthquake of magnitude 6.2 jolted the same area in Kerman province, injuring at least 18 people and damaging about 20 houses.
Most of the injured in the quake west of Tehran were hurt while trying to run out of buildings and were released from hospital after treatment, IRNA quoted the country's Emergency Medical Services as saying.
The quake is an aftershock of a 5.2 magnitude quake on Dec. 20 that killed two people. It was also felt in Tehran where many residents spent the night outside in cars, or in sport facilities and other buildings turned into rescue centres, local news agencies said.
Crisscrossed by several major geological fault lines, Iran is one of the world's most quake-prone countries. In 2003, a magnitude 6.6 quake in Kerman province killed 31,000 people and flattened the ancient city of Bam.
(Reporting by Dubai newsroom; Editing by Matthew Mpoke Bigg and Hugh Lawson)
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