Abstract

We have calculated empirical attenuation curves for the local magnitude scale (ML) in the Alborz region of northern Iran. The maximum trace amplitudes derived from synthetic Wood–Anderson seismograms of 1290 records of 59 events in the distance range of 8.5–550 km recorded by the short-period Iranian Seismic Telemetry Network (ISTN) were inverted for the attenuation curve, magnitudes, and station corrections. The earthquakes ranged from ML3.25 to 5.65 and were recorded at 26 stations in the region. We used both nonparametric and parametric least-squares methods for inversion. The resulting parametric equation is logA0=-1.1725log(R)-0.0021R-0.4450. The two methods yielded very similar results and are very close to Richter’s original attenuation curve for southern California. The station corrections vary between -0.42 and +0.47 suggesting that local site effects may have a strong influence on the amplitudes.

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