Zari BORDBAR - Expert, Institute of Geophysics, University of Tehran, Tehran, Iran
Mohammad Reza HATAMI - Assistant Professor, Institute of Geophysics, University of Tehran, Tehran, Iran
Amin ABBASI - Researcher, Institute of Geophysics, University of Tehran, Tehran, Iran

On August 11, 2012, two earthquakes of Mw = 6.5 and Mw = 6.3 took place in part of the Western Alborz seismotectonic province, Ahar-Varzaqhan region.We processed the phase data recorded in 8 seismic stations during 2006-2012 using Wadati method. Temporal variations of Vp/Vs were studied as a tool in earthquake precursory researches in these earthquakes. We impose a number of restrictions on the computation. The number of stations involved in this process is more than 3 and recorded earthquakes withM ≥ Mc. Under these restrictions, the study shows that Vp/Vs in and around Ahar-Varzaqhan study area normal-low-normal process a few months before main shock occurrence

Ahar-Varzaghan Earthquake, Ratio of Shear and Compressional Wave Velocities,Earthquake Prediction