A series of eight earthquakes hit the Iran-Iraq border area and rattled Baghdad on Thursday, apparently the aftershocks of a temblor that struck the mountainous region in November and killed over 530 people.
Four people suffered minor injuries in Iran, state television reported.
All the earthquakes struck within an hour of each other, beginning at 0659 GMT. Six had a preliminary magnitude of at least 5, while two registered at magnitude 4. Scientists consider earthquakes of magnitude 5 as moderate.
Iranian authorities offered similar figures for the earthquakes on state television. All the information could change as scientists examine the data.
Iranian state television said online that people rushed into the streets as the temblors hit. In Baghdad, people felt a quake shake the Iraqi capital, followed by what felt like aftershocks.
All the earthquakes struck at a depth of 10 kilometers , according to the USGS. Earthquakes at magnitude 5 can cause considerable damage. The temblors also all were very shallow, which causes more ground shaking and potential damage, particularly in places without strict building codes.
In November, a major 7.3 magnitude earthquake struck the same region, killing over 530 people and injuring thousands in Iran alone. In Iraq, nine people were killed and 550 were injured, all in the country's northern Kurdish region, according to the United Nations.
Randy Baldwin, a geophysicist with the USGS' National Earthquake Information Center in Golden, Colorado, said the earthquakes all appeared to be aftershocks from the November temblor.
That area is home to many shallow faults, he said. "It's ongoing activity there," Baldwin told The Associated Press. "If there was a stressed fault that's ready to move, they happen like that until the stresses are relieved, so it's not too unusual.