The province of Khorasan, extending from 30.0N to 39.0N and from 55.0E to60.0E, is the region with the highest seismic activity in the Iranian plateau. We employed broad-band seismograms which were recorded by the Khorasan Seismic Network (KHSN) during 2000 to 2006.In this study, we used zero-to-peak amplitudes from synthetic Wood-Anderson seismograms to develop a local magnitude scale, for the province of Khorasan, through evaluation of an appropriate –logA0 attenuation function and station magnitude corrections. The original data consist of 1506 arrivals at 6 three-component stations, from 205 earthquakes. In the range 10-600 km of epicentral distance, the best fit is given by: -log A0 = (1.377 •} 0.054) log(R/100) + (0.0019 •} 0.0001)(R-100) + 3.0To test the stability of the inversion and also to estimate the variances involved in station corrections, the Bootstrap resampling approach was applied using 3000 repeated inversions on randomly sampled data sets. Station corrections, which allow for a significant reduction of ML residuals range between -0.27 and 0.17 magnitude units. The calculated value of k =0.0019 confirms that in this range of distance seismic waves could propagates through a low-Q value in Khorasan region in agreement with the result of previous studies.

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