Kope Dagh Earthquake of 1 May 1929, Mw=7.3

Kope Dagh Earthquake of 1 May 1929, Mw=7.3

This large-magnitude earthquake killed more than 3800 people (the exact number is unknown) and injured more than 1100 people in 300 villages in the Central Kopeh Dagh Shear Zone (CKDSZ), northeast of Iran. Wilson (1930), based on the Daily Telegraph of 6 May 1929, wrote that: “a cleft three yards wide [2.7 m] was opened between the towns [villages] of Khaki and Baghan to the east of the Tehran-Isfahan road, the cleft extending to a distance of 28.9 km. The towns of Quchan and Robat also suffered severely, huge fissures in the ground being opened up, one being, according to a report in the Times of 9 May 1929, 38.9km long and 2.7m wide. The total casualties were subsequently given in an official report from a government inspector at Quchan as 3253 persons killed, 1121 injured, 83 villages destroyed, and 6542 cattle killed” (Wilson, 1930). The distance between Kakoli and Baghan, where earthquake faulting along the Baghan fault was reported, is 36 km. M. Pashinskiy, chief of the Khairabad Meteorological Station near the Russian border (in Popov, 1940), wrote that there was a horrifying crash from the talus in the mountains and landslides and fissures in the surrounding areas. Nazarevsky (1932) reported some earthquake fissures at the area immediately northeast of the Germab village in southern Russia (present Turkmenistan), along the northeastern embankment of the Mergen Ulya River running NW–SE parallel to the river, indicating sliding along the northern embankment of the river course. He also added that all buildings at Garmab were destroyed and the Sakiz Ab River to the south of Garmab was waterlogged. The earthquake produced coseismic ground ruptures about 70 km in length with a vertical motion of about 2 m on the northeast side of the Baghan fault. No fresh strike-slip motion was documented in 1974 when the area was visited (Tchalenko et al., 1974b; Tchalenko, 1975; Ambraseys and Melville, 1982). The Baghan right-lateral strike-slip fault is a member of the “CKDSZ” of closely spaced NW–SE trending parallel right-lateral strike-slip faults cutting and displacing the Kopeh Dagh fold-and-thrust belt. The CKDSZ resembles the Eastern California Shear Zone (Sauber et al., 1986, 1994). A total right-lateral offset of about 10km can be measured between the displaced Upper Cretaceous Abderaz Formation outcrops at about 37°35′ N – 58°00′ E (Afshar-Harb, 1979; Hollingsworth et al., 2006). The total length of the fault is 80 km and is capable of right-lateral slip of about 3.0 m (Wells and Coppersmith, 1994). Hollingsworth et al. (2008) and Shabanian et al. (2009a) suggested a right-lateral slip-rate of 1.0 and 2.8 mm/year, respectively (Berberian, 2014).