An earthquake of moment magnitude Mw 7.3 struck the mountainous Iran-Iraq border region at 18:18 UTC (21:18 local time in Iraq, 21:48 local time in Iran) on Sunday November 12, according to the United States Geological Survey (USGS). The epicenter was located 20 mi (32 km) south of Halabja (pop. ~110,000), Sulaymaniyah governate, Iraq. The quake was shallow, at a depth of 12 mi (19 km). The strongest shaking, with a Modified Mercalli Intensity (MMI) of VIII (Severe), was felt by about 35,000 people. Shaking of MMI VI (Strong) or above was felt by about 16 million people. Aftershocks have also caused some damage. As of 09:00 UTC, November 15, there have been 18 recorded quakes of Mw 4.0 or greater, and one of Mw 5.0. The most recent USGS ShakeMap (version 6 as of 01:26 on November 14) shows a far broader region affected by MMI VI and above than previous versions. IRAN: The number of buildings damaged is unclear. Media are reporting estimates from 12,000 to 30,000 homes damaged, mostly in western Iran. A spokesperson from Iran’s National Disaster Management Organization (NDMO) stated that 123 settlements have been damaged. The worst damage is reported in in the Kermanshah province of western Iran. In the town of Sarpol-e Zahab (pop. ~35,000) about 90% of buildings are reported destroyed. The hospital, which is Kermanshah province’s primary hospital, is reported to be severely damaged. More than 140 fatalities are reported in the town. Notable damage is also reported in the towns and cities of, Qasr-e-Shirin (pop. ~15,000), Kermanshah (pop. ~850,000), Eslamabad-e-Gharb (pop. ~89,000), Javanrud (pop. ~51,000), Qasr-e Shirin (pop. ~15,000), Salas Babajani (pop. ~50,000) and Paveh (pop. ~24,000). This list is not comprehensive. Damage is extensive and not limited to Kermanshah province and regions close to the epicenter. Media report damage in Ilam (pop. ~210,000), Ilam Province, Khorramabad (pop. ~350,000), Lorestan Province, and Borujerd (pop. ~240,000), Lorestan Province, which are about 170 mi (280 km) from the epicenter. In Borujerd, 354 buildings are reported damaged. Hundreds of rural buildings are also thought to have been damaged or destroyed. Damage has been particularly severe to state-subsidized buildings constructed under the Mehr housing program, which aimed to provide affordable housing for poorer citizens, and where construction regulations may not have been followed. Damage to power, water and telecommunication networks is reported, hampering communication and relief work. 90 percent of utilities have been restored, but some of the worst-affected areas are still without electricity or water 48 hours after the event. Landslides have blocked roads, but these have reportedly reopened as of November 15. The NDMO reports that 435 people have been killed and 9,397 injured. IRAQ: The reported damage is less severe in Iraq. A smaller, more sparsely-populated area was affected by the most severe shaking. The worst-affected settlements are currently reported to be Khanaquin (pop. ~150,000) and Darbandikhan (pop. <20,000), Sulimaniyah governate. The local hospital is reported to be damaged and without electricity. There is concern that the Derbandakhan Dam, which was close to the epicenter, has been damaged. Its condition is currently being evaluated. Iraqi officials say at least 9 people have been killed and 535 injured. GEOLOGICAL CONTEXT: The earthquake was the eighth strongest to hit the region since 1900, and the strongest to hit within 150 mi (250 km) in the last century. It occurred along the boundary between the Arabia and Eurasia plates as a result of oblique-thrust faulting where the plates converge. The size and mechanism of the quake mean that it is better thought of as a “slip over a larger fault area” than a point event, according to the USGS. Events of this magnitude may have a length of about 40 mi (65 km), and damage will therefore occur at some distance from the designated epicenter.