Salmas Earthquake of 7 May 1930, Mw=7.1

Preceded by an alarming foreshock of Ms 5.4 (10:03 local time on 6 May 1930), which forced the people to stay outdoors at night, the mainshock (01:34 local time on 7 May 1930) destroyed two cities of Dilman (Salmas) and Kohneh Shar, killing about 2514 people in the Salmas Plain and the surrounding mountains of the northwest Iran. The alarming Ms 5.4 foreshock of 6 May 1930 (07:03 UTC) caused localized destruction and casualties in a small region centered at 38.15N–44.75E, south of the city of Salmas with possible short ground rupture. Several eyewitnesses recorded the coseismic surface faulting and associated ground deformation during the 1930 Salmas mainshock. The emergency vehicles were unable to approach Salmas from Tehran, as new rifts had been formed. The Tabriz Newspaper (10 May 1930) quoted a cable dated 7 May 1930 that at Derik cracks appeared in the mountains (Tchalenko and rberian, 1974; Berberian and Tchalenko, 1976a). This indicates that the Derik fault (a short fault conjugate to the Salmas fault) moved prior to the 8 May M 6.2 aftershock, possibly during the mainshock, which ruptured along the Salmas fault. The same newspaper (24 May 1930) described rockfalls and cracks in the mountains west of Kohneh Shahr. The cracks started from Boghaz-e Zarindarreh and continued to the Kuh-e Shomal. The cracks after Chahriq crossed the Aliguli hills and then turned southward to Qarni Yarekh (Tchalenko and Berberian, 1974; Berberian and Tchalenko, 1976a). The fractured section (from Zarrindarreh to Qarni Yarekh) covers a section of the Salmas coseismic surface fault of more than 10 km (Berberian, 2014).