Update at 2:19 a.m. ET:
Iranian state television has now raised the death toll of the earthquakes to over 250 and at least 2,000 injured, according to the Associated Press.
"Images broadcast on the main news channel showed dozens of families of sleeping outdoors in parks, with blankets laid out on the ground. Some were crying, others shivering from chilly weather in the mountainous region hit by the quake in the northwestern part of the country."
Update at 5 p.m. ET:
The death toll is rising in a pair of earthquakes in northwestern Iran. At least 180 people have died, the Associated Press reports, and more than 1,300 others have been injured.
Our Original Post Continues:
Tabriz is in the very northwestern portion of Iran and lies close to northern neighbors Armenia and Azerbaijan. Turkey and Iraq are to the west; the Caspian Sea is close and to the east.
There've been several aftershocks. Al Jazeera reports at least 400 people have been hurt, and thousands of frightened people fled into the streets of Tabriz. While major damage is not reported in the city of 1.5 million people, the report says dozens of villages closer to the epicenter are damaged or destroyed, and a a great number of injured people are expected.
The first quake's magnitude was 6.4 and the second was slightly less powerful, at 6.3. As the USGS says, "magnitude measures the energy released at the source of the earthquake." Just one tremor at this magnitude will damage poorly constructed buildings and could even cause walls to collapse in 'substantial buildings'. Many buildings could be shifted off their foundations.