Though the coseismic surface deformation observed in the SAR interferogram closely resembles folding, the overall topography does not, because of inherited topography associated with earlier geological deformation. We argue that the Sefidabeh fault originally formed by coalescence of many small fault segments, and has grown in length at about 2 cm yr в€’1 in the past 100 ka. From the cumulative, dated uplift and knowledge of the surface displacements due to an earthquake sequence, we estimate that в€ј120 such events have occurred in the past 100 ka, with an average recurrence interval of 830 yr, and an average convergence rate of 1.5 mm yr в€’1 on the Sefidabeh thrust each estimate has an uncertainty of a factor of two, either way. We also present U/Th dates of в€ј100 ka for lake deposits uplifted by the growing ridge. In this study we present a SAR interferogram that precisely determines the location and amount of coseismic surface displacements, showing that the earthquakes in the Sefidabeh sequence probably occurred on en-echelon fault segments associated with three stepping ridges.

In an earlier study of the teleseismic waveforms, the geomorphology and the faulting in the epicentral region, it was suggested that these earthquakes were associated with the growth of a ridge above a blind thrust fault system, whose activity could be detected by its effect on the surface drainage. In 1994, three shallow earthquakes of M wв€ј 6 occurred close together on blind thrusts near Sefidabeh in eastern Iran.

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