The seismicity of Iran. The Firuzabad (Nehavend) earthquake of 16 August 1958

The Firuzabad (Iran) earthquake of the 16th August 1958 had a smaller magnitude (il/ = 6.6) than did the last major earthquake in the same area which occurred on the 13th December 1957, and had a 7.1 magnitude. The Firuzabad earthquake killed 132 and injured about 200 people in 170 villages. It affected an area of 1,100 square kilometres -within which 2,500 housing units were destroyed or damaged beyond repair. The earthquake had its macroseismic epicentre somewhat southeast of the 1957 earthquake and the shock was felt over an area of 80,000 square kilometres. The damage pattern from the Firuzabad earthquake did not resemble that of the 1957 shock, in that the Firuzabad earthquake affected a smaller region but was the more intense of the two. In contrast, the 1957 earthquake had a somewhat more moderate surface intensity over a much wider area. The Firuzabad earthquake was associated with a fault-zone at least 20 kilometres long. This earthquake and the seismic events of the previous year as well as the aftershocks of the 21st of September 1958, show quite clearly a progressive expansion of seismic activity along a northwest-southwest axis in the Zagros mountains