The Salmas (Iran) earthquake of May 6th, 1930

Field investigations and bibliographical research into the little-known but important Salmas earthquake in Northwest Azarbaijan (Iran) provided the following results. The morning before the earthquake, a foreshock (Mb — 5.4) centered, as the main shock, in the Salmas Plain, killed about 25 people and incited a great part of the population to spend the following night out of doors. The main shock (Mb = 7.3) occurred the following night, on 6 May 1930 at 22h34m27s GMT and destroyed about 60 villages and 40 churches, killing about 2514 people, both in the Salmas Plain and in the surrounding mountains. Its macroseismic epicentre was at approximately 3S.15N 44.70E. The main shock was associated with 2 surface faults, with a maximum horizontal displacement of 4 m and vertical displacement of over 5 m; the combined action of these faults was a relative lowering, and a displacement to the east, of the Salmas Plain. Two days later, the strongest aftershock destroyed one village at the northern edge of the Salmas Plain.